Prove $sum_i=0^nbinomm+ii=binomm+n+1n$ (another Hockey-Stick Identity?) [closed]What is the story behind $n+1 choose k = n choose k + n choose k-1$?Another Hockey Stick IdentityIdentity involving binomial coefficients: $sum_j=0^i (-1)^i+jbinom n-ji-jbinom mj=sum_j=0^i (-1)^i+jbinom n-j+ki-jbinom m+kj$Prove $sumlimits_i=0^nbinomi+k-1k-1=binomn+kk$ (a.k.a. Hockey-Stick Identity)Proof of the Hockey-Stick Identity: $sumlimits_t=0^n binom tk = binomn+1k+1$Prove the identity $sum^n_k=0binomm+kk = binomn+m+1n$Hockey-Stick Theorem for Multinomial CoefficientsBinomial identity $sum_i=0^n-1-jbinomni+jbinomi+jj(-1)^i=binomnj(-1)^n+j+1$Another Hockey Stick IdentityEnumerative interpretation of generalized $q$-hockey stick identityHint on how to prove the identity $sum_0 leq k leq n binomkm = binomn + 1m + 1$Proving Pascal's Triangle and Hockey-Stick Identity using Combinatorics
Is it legal for company to use my work email to pretend I still work there?
Why does Kotter return in Welcome Back Kotter?
How old can references or sources in a thesis be?
Is it important to consider tone, melody, and musical form while writing a song?
Which models of the Boeing 737 are still in production?
How to find program name(s) of an installed package?
Can an x86 CPU running in real mode be considered to be basically an 8086 CPU?
Maximum likelihood parameters deviate from posterior distributions
Why did the Germans forbid the possession of pet pigeons in Rostov-on-Don in 1941?
What does CI-V stand for?
How to write a macro that is braces sensitive?
I’m planning on buying a laser printer but concerned about the life cycle of toner in the machine
strToHex ( string to its hex representation as string)
What do you call a Matrix-like slowdown and camera movement effect?
LaTeX closing $ signs makes cursor jump
What typically incentivizes a professor to change jobs to a lower ranking university?
What are these boxed doors outside store fronts in New York?
Today is the Center
Smoothness of finite-dimensional functional calculus
"to be prejudice towards/against someone" vs "to be prejudiced against/towards someone"
The Two and the One
Theorem, big Paralist and Amsart
TGV timetables / schedules?
How do we improve the relationship with a client software team that performs poorly and is becoming less collaborative?
Prove $sum_i=0^nbinomm+ii=binomm+n+1n$ (another Hockey-Stick Identity?) [closed]
What is the story behind $n+1 choose k = n choose k + n choose k-1$?Another Hockey Stick IdentityIdentity involving binomial coefficients: $sum_j=0^i (-1)^i+jbinom n-ji-jbinom mj=sum_j=0^i (-1)^i+jbinom n-j+ki-jbinom m+kj$Prove $sumlimits_i=0^nbinomi+k-1k-1=binomn+kk$ (a.k.a. Hockey-Stick Identity)Proof of the Hockey-Stick Identity: $sumlimits_t=0^n binom tk = binomn+1k+1$Prove the identity $sum^n_k=0binomm+kk = binomn+m+1n$Hockey-Stick Theorem for Multinomial CoefficientsBinomial identity $sum_i=0^n-1-jbinomni+jbinomi+jj(-1)^i=binomnj(-1)^n+j+1$Another Hockey Stick IdentityEnumerative interpretation of generalized $q$-hockey stick identityHint on how to prove the identity $sum_0 leq k leq n binomkm = binomn + 1m + 1$Proving Pascal's Triangle and Hockey-Stick Identity using Combinatorics
$begingroup$
Let $n$ be a nonnegative integer, and $m$ a positive integer. Could someone explain to me why the identity
$$
sum_i=0^nbinomm+ii=binomm+n+1n
$$
holds?
discrete-mathematics binomial-coefficients
$endgroup$
closed as off-topic by Hanul Jeon, Leucippus, José Carlos Santos, Eevee Trainer, Parcly Taxel Mar 26 at 3:27
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Hanul Jeon, Leucippus, José Carlos Santos, Eevee Trainer, Parcly Taxel
|
show 2 more comments
$begingroup$
Let $n$ be a nonnegative integer, and $m$ a positive integer. Could someone explain to me why the identity
$$
sum_i=0^nbinomm+ii=binomm+n+1n
$$
holds?
discrete-mathematics binomial-coefficients
$endgroup$
closed as off-topic by Hanul Jeon, Leucippus, José Carlos Santos, Eevee Trainer, Parcly Taxel Mar 26 at 3:27
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Hanul Jeon, Leucippus, José Carlos Santos, Eevee Trainer, Parcly Taxel
$begingroup$
You may want to see this: math.stackexchange.com/questions/1784613/…. (Replace their $r$ with your $n$ and their $n$ with your $m+1$.)
$endgroup$
– Minus One-Twelfth
Mar 22 at 3:17
$begingroup$
This is easy to show by induction ... try it ?
$endgroup$
– Donald Splutterwit
Mar 22 at 3:22
$begingroup$
Alternative answer ... Yes someone can explain it !
$endgroup$
– Donald Splutterwit
Mar 22 at 3:23
$begingroup$
@DonaldSplutterwit I know that it's done by induction but still sure how. So yes, I've tried it.
$endgroup$
– Ben
Mar 22 at 4:05
$begingroup$
@MinusOne-Twelfth It's almost impossible to keep the terms straight but I substituted my stuff over to the best reply on that post but it still isn't very clear. Do you know the induction method?
$endgroup$
– Ben
Mar 22 at 4:06
|
show 2 more comments
$begingroup$
Let $n$ be a nonnegative integer, and $m$ a positive integer. Could someone explain to me why the identity
$$
sum_i=0^nbinomm+ii=binomm+n+1n
$$
holds?
discrete-mathematics binomial-coefficients
$endgroup$
Let $n$ be a nonnegative integer, and $m$ a positive integer. Could someone explain to me why the identity
$$
sum_i=0^nbinomm+ii=binomm+n+1n
$$
holds?
discrete-mathematics binomial-coefficients
discrete-mathematics binomial-coefficients
asked Mar 22 at 3:15
BenBen
61
61
closed as off-topic by Hanul Jeon, Leucippus, José Carlos Santos, Eevee Trainer, Parcly Taxel Mar 26 at 3:27
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Hanul Jeon, Leucippus, José Carlos Santos, Eevee Trainer, Parcly Taxel
closed as off-topic by Hanul Jeon, Leucippus, José Carlos Santos, Eevee Trainer, Parcly Taxel Mar 26 at 3:27
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question is missing context or other details: Please provide additional context, which ideally explains why the question is relevant to you and our community. Some forms of context include: background and motivation, relevant definitions, source, possible strategies, your current progress, why the question is interesting or important, etc." – Hanul Jeon, Leucippus, José Carlos Santos, Eevee Trainer, Parcly Taxel
$begingroup$
You may want to see this: math.stackexchange.com/questions/1784613/…. (Replace their $r$ with your $n$ and their $n$ with your $m+1$.)
$endgroup$
– Minus One-Twelfth
Mar 22 at 3:17
$begingroup$
This is easy to show by induction ... try it ?
$endgroup$
– Donald Splutterwit
Mar 22 at 3:22
$begingroup$
Alternative answer ... Yes someone can explain it !
$endgroup$
– Donald Splutterwit
Mar 22 at 3:23
$begingroup$
@DonaldSplutterwit I know that it's done by induction but still sure how. So yes, I've tried it.
$endgroup$
– Ben
Mar 22 at 4:05
$begingroup$
@MinusOne-Twelfth It's almost impossible to keep the terms straight but I substituted my stuff over to the best reply on that post but it still isn't very clear. Do you know the induction method?
$endgroup$
– Ben
Mar 22 at 4:06
|
show 2 more comments
$begingroup$
You may want to see this: math.stackexchange.com/questions/1784613/…. (Replace their $r$ with your $n$ and their $n$ with your $m+1$.)
$endgroup$
– Minus One-Twelfth
Mar 22 at 3:17
$begingroup$
This is easy to show by induction ... try it ?
$endgroup$
– Donald Splutterwit
Mar 22 at 3:22
$begingroup$
Alternative answer ... Yes someone can explain it !
$endgroup$
– Donald Splutterwit
Mar 22 at 3:23
$begingroup$
@DonaldSplutterwit I know that it's done by induction but still sure how. So yes, I've tried it.
$endgroup$
– Ben
Mar 22 at 4:05
$begingroup$
@MinusOne-Twelfth It's almost impossible to keep the terms straight but I substituted my stuff over to the best reply on that post but it still isn't very clear. Do you know the induction method?
$endgroup$
– Ben
Mar 22 at 4:06
$begingroup$
You may want to see this: math.stackexchange.com/questions/1784613/…. (Replace their $r$ with your $n$ and their $n$ with your $m+1$.)
$endgroup$
– Minus One-Twelfth
Mar 22 at 3:17
$begingroup$
You may want to see this: math.stackexchange.com/questions/1784613/…. (Replace their $r$ with your $n$ and their $n$ with your $m+1$.)
$endgroup$
– Minus One-Twelfth
Mar 22 at 3:17
$begingroup$
This is easy to show by induction ... try it ?
$endgroup$
– Donald Splutterwit
Mar 22 at 3:22
$begingroup$
This is easy to show by induction ... try it ?
$endgroup$
– Donald Splutterwit
Mar 22 at 3:22
$begingroup$
Alternative answer ... Yes someone can explain it !
$endgroup$
– Donald Splutterwit
Mar 22 at 3:23
$begingroup$
Alternative answer ... Yes someone can explain it !
$endgroup$
– Donald Splutterwit
Mar 22 at 3:23
$begingroup$
@DonaldSplutterwit I know that it's done by induction but still sure how. So yes, I've tried it.
$endgroup$
– Ben
Mar 22 at 4:05
$begingroup$
@DonaldSplutterwit I know that it's done by induction but still sure how. So yes, I've tried it.
$endgroup$
– Ben
Mar 22 at 4:05
$begingroup$
@MinusOne-Twelfth It's almost impossible to keep the terms straight but I substituted my stuff over to the best reply on that post but it still isn't very clear. Do you know the induction method?
$endgroup$
– Ben
Mar 22 at 4:06
$begingroup$
@MinusOne-Twelfth It's almost impossible to keep the terms straight but I substituted my stuff over to the best reply on that post but it still isn't very clear. Do you know the induction method?
$endgroup$
– Ben
Mar 22 at 4:06
|
show 2 more comments
2 Answers
2
active
oldest
votes
$begingroup$
$newcommandbbx[1],bbox[15px,border:1px groove navy]displaystyle#1,
newcommandbraces[1]leftlbrace,#1,rightrbrace
newcommandbracks[1]leftlbrack,#1,rightrbrack
newcommandddmathrmd
newcommandds[1]displaystyle#1
newcommandexpo[1],mathrme^#1,
newcommandicmathrmi
newcommandmc[1]mathcal#1
newcommandmrm[1]mathrm#1
newcommandpars[1]left(,#1,right)
newcommandpartiald[3][]fracpartial^#1 #2partial #3^#1
newcommandroot[2][],sqrt[#1],#2,,
newcommandtotald[3][]fracmathrmd^#1 #2mathrmd #3^#1
newcommandverts[1]leftvert,#1,rightvert$
beginalign
&bbox[10px,#ffd]sum_i = 0^nm + i choose i =
sum_i = 0^npars-1^i-m -i + i - 1 choose i
\[5mm] = &
sum_i = 0^npars-1^i-m - 1 choose i =
sum_i = 0^npars-1^ibracksz^ipars1 + z^-m - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1
sum_i = 0^npars-,1 over z^i
=
bracksz^0pars1 + z^-m - 1,
pars-1/z^n + 1 - 1 over pars-1/z - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1,
pars-1^n + 1 - z^n + 1 over -1 - z
,z over z^n + 1
\[5mm] = &
bracksz^npars1 + z^-m - 2,
bracksz^n + 1 - pars-1^n + 1 =
pars-1^nbracksz^npars1 + z^-m - 2
\[5mm] = &
pars-1^n-m - 2 choose n =
pars-1^nbracksm + 2 + n - 1choose npars-1^n
\[5mm] = & bbxm + n + 1 choose n
endalign
$endgroup$
$begingroup$
The color#ffd
is so ease to work with :)
$endgroup$
– Le Anh Dung
Mar 22 at 5:52
2
$begingroup$
@LeAnhDung It clearly shows the very beginning while the box shows the very end.
$endgroup$
– Felix Marin
Mar 22 at 5:54
add a comment |
$begingroup$
We have
$$sum_q=0^n m+qchoose q = sum_qge 0 m+qchoose q [[0le qle n]]
\ = sum_qge 0 m+qchoose q [z^n] fracz^q1-z
= [z^n] frac11-z sum_qge 0 m+qchoose q z^q
\= [z^n] frac11-z frac1(1-z)^m+1
= [z^n] frac1(1-z)^m+2
= n+m+1choose n.$$
$endgroup$
add a comment |
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
$newcommandbbx[1],bbox[15px,border:1px groove navy]displaystyle#1,
newcommandbraces[1]leftlbrace,#1,rightrbrace
newcommandbracks[1]leftlbrack,#1,rightrbrack
newcommandddmathrmd
newcommandds[1]displaystyle#1
newcommandexpo[1],mathrme^#1,
newcommandicmathrmi
newcommandmc[1]mathcal#1
newcommandmrm[1]mathrm#1
newcommandpars[1]left(,#1,right)
newcommandpartiald[3][]fracpartial^#1 #2partial #3^#1
newcommandroot[2][],sqrt[#1],#2,,
newcommandtotald[3][]fracmathrmd^#1 #2mathrmd #3^#1
newcommandverts[1]leftvert,#1,rightvert$
beginalign
&bbox[10px,#ffd]sum_i = 0^nm + i choose i =
sum_i = 0^npars-1^i-m -i + i - 1 choose i
\[5mm] = &
sum_i = 0^npars-1^i-m - 1 choose i =
sum_i = 0^npars-1^ibracksz^ipars1 + z^-m - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1
sum_i = 0^npars-,1 over z^i
=
bracksz^0pars1 + z^-m - 1,
pars-1/z^n + 1 - 1 over pars-1/z - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1,
pars-1^n + 1 - z^n + 1 over -1 - z
,z over z^n + 1
\[5mm] = &
bracksz^npars1 + z^-m - 2,
bracksz^n + 1 - pars-1^n + 1 =
pars-1^nbracksz^npars1 + z^-m - 2
\[5mm] = &
pars-1^n-m - 2 choose n =
pars-1^nbracksm + 2 + n - 1choose npars-1^n
\[5mm] = & bbxm + n + 1 choose n
endalign
$endgroup$
$begingroup$
The color#ffd
is so ease to work with :)
$endgroup$
– Le Anh Dung
Mar 22 at 5:52
2
$begingroup$
@LeAnhDung It clearly shows the very beginning while the box shows the very end.
$endgroup$
– Felix Marin
Mar 22 at 5:54
add a comment |
$begingroup$
$newcommandbbx[1],bbox[15px,border:1px groove navy]displaystyle#1,
newcommandbraces[1]leftlbrace,#1,rightrbrace
newcommandbracks[1]leftlbrack,#1,rightrbrack
newcommandddmathrmd
newcommandds[1]displaystyle#1
newcommandexpo[1],mathrme^#1,
newcommandicmathrmi
newcommandmc[1]mathcal#1
newcommandmrm[1]mathrm#1
newcommandpars[1]left(,#1,right)
newcommandpartiald[3][]fracpartial^#1 #2partial #3^#1
newcommandroot[2][],sqrt[#1],#2,,
newcommandtotald[3][]fracmathrmd^#1 #2mathrmd #3^#1
newcommandverts[1]leftvert,#1,rightvert$
beginalign
&bbox[10px,#ffd]sum_i = 0^nm + i choose i =
sum_i = 0^npars-1^i-m -i + i - 1 choose i
\[5mm] = &
sum_i = 0^npars-1^i-m - 1 choose i =
sum_i = 0^npars-1^ibracksz^ipars1 + z^-m - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1
sum_i = 0^npars-,1 over z^i
=
bracksz^0pars1 + z^-m - 1,
pars-1/z^n + 1 - 1 over pars-1/z - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1,
pars-1^n + 1 - z^n + 1 over -1 - z
,z over z^n + 1
\[5mm] = &
bracksz^npars1 + z^-m - 2,
bracksz^n + 1 - pars-1^n + 1 =
pars-1^nbracksz^npars1 + z^-m - 2
\[5mm] = &
pars-1^n-m - 2 choose n =
pars-1^nbracksm + 2 + n - 1choose npars-1^n
\[5mm] = & bbxm + n + 1 choose n
endalign
$endgroup$
$begingroup$
The color#ffd
is so ease to work with :)
$endgroup$
– Le Anh Dung
Mar 22 at 5:52
2
$begingroup$
@LeAnhDung It clearly shows the very beginning while the box shows the very end.
$endgroup$
– Felix Marin
Mar 22 at 5:54
add a comment |
$begingroup$
$newcommandbbx[1],bbox[15px,border:1px groove navy]displaystyle#1,
newcommandbraces[1]leftlbrace,#1,rightrbrace
newcommandbracks[1]leftlbrack,#1,rightrbrack
newcommandddmathrmd
newcommandds[1]displaystyle#1
newcommandexpo[1],mathrme^#1,
newcommandicmathrmi
newcommandmc[1]mathcal#1
newcommandmrm[1]mathrm#1
newcommandpars[1]left(,#1,right)
newcommandpartiald[3][]fracpartial^#1 #2partial #3^#1
newcommandroot[2][],sqrt[#1],#2,,
newcommandtotald[3][]fracmathrmd^#1 #2mathrmd #3^#1
newcommandverts[1]leftvert,#1,rightvert$
beginalign
&bbox[10px,#ffd]sum_i = 0^nm + i choose i =
sum_i = 0^npars-1^i-m -i + i - 1 choose i
\[5mm] = &
sum_i = 0^npars-1^i-m - 1 choose i =
sum_i = 0^npars-1^ibracksz^ipars1 + z^-m - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1
sum_i = 0^npars-,1 over z^i
=
bracksz^0pars1 + z^-m - 1,
pars-1/z^n + 1 - 1 over pars-1/z - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1,
pars-1^n + 1 - z^n + 1 over -1 - z
,z over z^n + 1
\[5mm] = &
bracksz^npars1 + z^-m - 2,
bracksz^n + 1 - pars-1^n + 1 =
pars-1^nbracksz^npars1 + z^-m - 2
\[5mm] = &
pars-1^n-m - 2 choose n =
pars-1^nbracksm + 2 + n - 1choose npars-1^n
\[5mm] = & bbxm + n + 1 choose n
endalign
$endgroup$
$newcommandbbx[1],bbox[15px,border:1px groove navy]displaystyle#1,
newcommandbraces[1]leftlbrace,#1,rightrbrace
newcommandbracks[1]leftlbrack,#1,rightrbrack
newcommandddmathrmd
newcommandds[1]displaystyle#1
newcommandexpo[1],mathrme^#1,
newcommandicmathrmi
newcommandmc[1]mathcal#1
newcommandmrm[1]mathrm#1
newcommandpars[1]left(,#1,right)
newcommandpartiald[3][]fracpartial^#1 #2partial #3^#1
newcommandroot[2][],sqrt[#1],#2,,
newcommandtotald[3][]fracmathrmd^#1 #2mathrmd #3^#1
newcommandverts[1]leftvert,#1,rightvert$
beginalign
&bbox[10px,#ffd]sum_i = 0^nm + i choose i =
sum_i = 0^npars-1^i-m -i + i - 1 choose i
\[5mm] = &
sum_i = 0^npars-1^i-m - 1 choose i =
sum_i = 0^npars-1^ibracksz^ipars1 + z^-m - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1
sum_i = 0^npars-,1 over z^i
=
bracksz^0pars1 + z^-m - 1,
pars-1/z^n + 1 - 1 over pars-1/z - 1
\[5mm] = &
bracksz^0pars1 + z^-m - 1,
pars-1^n + 1 - z^n + 1 over -1 - z
,z over z^n + 1
\[5mm] = &
bracksz^npars1 + z^-m - 2,
bracksz^n + 1 - pars-1^n + 1 =
pars-1^nbracksz^npars1 + z^-m - 2
\[5mm] = &
pars-1^n-m - 2 choose n =
pars-1^nbracksm + 2 + n - 1choose npars-1^n
\[5mm] = & bbxm + n + 1 choose n
endalign
answered Mar 22 at 5:40
Felix MarinFelix Marin
68.9k7110147
68.9k7110147
$begingroup$
The color#ffd
is so ease to work with :)
$endgroup$
– Le Anh Dung
Mar 22 at 5:52
2
$begingroup$
@LeAnhDung It clearly shows the very beginning while the box shows the very end.
$endgroup$
– Felix Marin
Mar 22 at 5:54
add a comment |
$begingroup$
The color#ffd
is so ease to work with :)
$endgroup$
– Le Anh Dung
Mar 22 at 5:52
2
$begingroup$
@LeAnhDung It clearly shows the very beginning while the box shows the very end.
$endgroup$
– Felix Marin
Mar 22 at 5:54
$begingroup$
The color
#ffd
is so ease to work with :)$endgroup$
– Le Anh Dung
Mar 22 at 5:52
$begingroup$
The color
#ffd
is so ease to work with :)$endgroup$
– Le Anh Dung
Mar 22 at 5:52
2
2
$begingroup$
@LeAnhDung It clearly shows the very beginning while the box shows the very end.
$endgroup$
– Felix Marin
Mar 22 at 5:54
$begingroup$
@LeAnhDung It clearly shows the very beginning while the box shows the very end.
$endgroup$
– Felix Marin
Mar 22 at 5:54
add a comment |
$begingroup$
We have
$$sum_q=0^n m+qchoose q = sum_qge 0 m+qchoose q [[0le qle n]]
\ = sum_qge 0 m+qchoose q [z^n] fracz^q1-z
= [z^n] frac11-z sum_qge 0 m+qchoose q z^q
\= [z^n] frac11-z frac1(1-z)^m+1
= [z^n] frac1(1-z)^m+2
= n+m+1choose n.$$
$endgroup$
add a comment |
$begingroup$
We have
$$sum_q=0^n m+qchoose q = sum_qge 0 m+qchoose q [[0le qle n]]
\ = sum_qge 0 m+qchoose q [z^n] fracz^q1-z
= [z^n] frac11-z sum_qge 0 m+qchoose q z^q
\= [z^n] frac11-z frac1(1-z)^m+1
= [z^n] frac1(1-z)^m+2
= n+m+1choose n.$$
$endgroup$
add a comment |
$begingroup$
We have
$$sum_q=0^n m+qchoose q = sum_qge 0 m+qchoose q [[0le qle n]]
\ = sum_qge 0 m+qchoose q [z^n] fracz^q1-z
= [z^n] frac11-z sum_qge 0 m+qchoose q z^q
\= [z^n] frac11-z frac1(1-z)^m+1
= [z^n] frac1(1-z)^m+2
= n+m+1choose n.$$
$endgroup$
We have
$$sum_q=0^n m+qchoose q = sum_qge 0 m+qchoose q [[0le qle n]]
\ = sum_qge 0 m+qchoose q [z^n] fracz^q1-z
= [z^n] frac11-z sum_qge 0 m+qchoose q z^q
\= [z^n] frac11-z frac1(1-z)^m+1
= [z^n] frac1(1-z)^m+2
= n+m+1choose n.$$
answered Mar 22 at 14:38
Marko RiedelMarko Riedel
41.2k340111
41.2k340111
add a comment |
add a comment |
$begingroup$
You may want to see this: math.stackexchange.com/questions/1784613/…. (Replace their $r$ with your $n$ and their $n$ with your $m+1$.)
$endgroup$
– Minus One-Twelfth
Mar 22 at 3:17
$begingroup$
This is easy to show by induction ... try it ?
$endgroup$
– Donald Splutterwit
Mar 22 at 3:22
$begingroup$
Alternative answer ... Yes someone can explain it !
$endgroup$
– Donald Splutterwit
Mar 22 at 3:23
$begingroup$
@DonaldSplutterwit I know that it's done by induction but still sure how. So yes, I've tried it.
$endgroup$
– Ben
Mar 22 at 4:05
$begingroup$
@MinusOne-Twelfth It's almost impossible to keep the terms straight but I substituted my stuff over to the best reply on that post but it still isn't very clear. Do you know the induction method?
$endgroup$
– Ben
Mar 22 at 4:06