User Ira Gessel

6 votes

A numerical matrix of power sum polynomials

answered May 16, 2023 at 18:33

6 votes

Accepted

Extended binomial coefficients and the gamma function

answered Feb 22, 2022 at 20:39

6 votes

Accepted

Tanglegrams and functional equations of M. Somos

answered Jan 23, 2022 at 19:16

6 votes

One generating function, two-fold sums

answered May 4, 2019 at 0:41

6 votes

Accepted

p-adic valuation of coefficients of generating function

answered May 15, 2019 at 18:50

6 votes

Proof of identity involving Stirling numbers of the second kind

answered Dec 5, 2017 at 19:49

6 votes

Proof of a combinatorial equation

answered Aug 23, 2018 at 20:35

6 votes

Integer-valued factorial ratios

answered Sep 19, 2020 at 15:44

6 votes

The number of permutations of given order

answered Nov 2, 2020 at 22:47

6 votes

Alternative proofs sought after for a certain identity

answered Dec 24, 2020 at 21:20

6 votes

Accepted

A convolution-type identity for the "major index"

answered Apr 29, 2021 at 21:31

6 votes

A certain type of combinatorial identity, involving de Montmort numbers

answered Oct 8, 2021 at 1:05

6 votes

What are some examples of interesting uses of the theory of combinatorial species?

answered Oct 30, 2014 at 21:00

6 votes

Proof of Stirling number symmetric formulas

answered Mar 1, 2016 at 4:17

6 votes

Hypergeometric identities

answered May 6, 2013 at 2:34

6 votes

Accepted

How to prove recursion formulas for Stirling numbers?

answered Oct 5, 2012 at 15:57

6 votes

Circular Permutations With Identical Objects

answered Jan 26, 2012 at 14:32

6 votes

Accepted

generating function for regular tournaments

answered Mar 16, 2012 at 21:10

5 votes

Polynomials from a Recurrence Relation

answered Dec 30, 2010 at 21:59

5 votes

Accepted

Trigonometric identity needed for sums involving secants

answered Feb 21, 2013 at 0:43

5 votes

Name of certain combinatorial numbers?

answered Mar 4, 2013 at 14:57

5 votes

Counting problems where unlabeled is easier than labeled

answered Mar 8, 2016 at 14:52

5 votes

Given A set $U$ and a set $\mathcal O$ of subsets of $U$, how many subsets of $\mathcal O$ have union $U$?

answered Jul 17, 2014 at 1:12

5 votes

Generate all non-isomorphic partitions $\pi = \{ \{1, ..., n-1\}, \{n\} \}$ for all graphs of order $n$

answered Jun 23, 2015 at 22:00

5 votes

Exponential of a specific hypergeometric series

answered Feb 8, 2014 at 17:23

5 votes

Number of Permutations?

answered Oct 18, 2013 at 23:53

5 votes

Accepted

A certain type of combinatorial identity, involving de Montmort numbers

answered Oct 8, 2021 at 2:20

5 votes

What alternatives are there to the binomial poset theory of generating function families?

answered May 9, 2021 at 21:14

5 votes

Non-arithmetic proof of the integrality of a rational expression

answered Jan 3, 2021 at 0:18

5 votes

Accepted

Sign-reversing involution proof of tree inversion generating function at $-1$ equals number of alternating permutations?

answered Oct 17, 2019 at 5:45

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191 Answers

A numerical matrix of power sum polynomials

Extended binomial coefficients and the gamma function

Tanglegrams and functional equations of M. Somos

One generating function, two-fold sums

p-adic valuation of coefficients of generating function

Proof of identity involving Stirling numbers of the second kind

Proof of a combinatorial equation

Integer-valued factorial ratios

The number of permutations of given order

Alternative proofs sought after for a certain identity

A convolution-type identity for the "major index"

A certain type of combinatorial identity, involving de Montmort numbers

What are some examples of interesting uses of the theory of combinatorial species?

Proof of Stirling number symmetric formulas

Hypergeometric identities

How to prove recursion formulas for Stirling numbers?

Circular Permutations With Identical Objects

generating function for regular tournaments

Polynomials from a Recurrence Relation

Trigonometric identity needed for sums involving secants

Name of certain combinatorial numbers?

Counting problems where unlabeled is easier than labeled

Given A set $U$ and a set $\mathcal O$ of subsets of $U$, how many subsets of $\mathcal O$ have union $U$?

Generate all non-isomorphic partitions $\pi = \{ \{1, ..., n-1\}, \{n\} \}$ for all graphs of order $n$

Exponential of a specific hypergeometric series

Number of Permutations?

A certain type of combinatorial identity, involving de Montmort numbers

What alternatives are there to the binomial poset theory of generating function families?

Non-arithmetic proof of the integrality of a rational expression

Sign-reversing involution proof of tree inversion generating function at $-1$ equals number of alternating permutations?