User Ira Gessel

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NE-Lattice paths from $(0,0)$ to $(n,n)$ with $k$ peaks

answered Nov 16, 2019 at 0:46

5 votes

Logarithm of the hypergeometric function

answered Jan 2, 2018 at 3:06

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Are there Prüfer sequences for rooted forests?

answered Oct 11, 2018 at 17:22

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A hypergeometric identity related to Bessel functions

answered Jun 29, 2019 at 2:46

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The number of Dyck paths of length $2n$ and height exactly $k$

answered Dec 27, 2018 at 17:06

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Binomial coefficient congruence modulo $p^n$

answered Oct 26, 2022 at 15:32

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Representing PSET as species

answered Jul 20, 2022 at 3:58

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5 different ways to define the same family of integer sequences

answered Aug 1 at 17:37

4 votes

$n$-th derivative of $\exp\left(-\frac{\lambda(x-\mu)^2}{2\mu^2x}\right)$

answered Apr 24 at 17:27

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Unconventional types of induction

answered Apr 29, 2023 at 0:11

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General case of the some $R$-recursions

answered Jan 24 at 19:03

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$R$-recursion for the A307389

answered Jan 25 at 3:37

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Is this a known symmetry of lattice paths?

answered Jan 9, 2023 at 15:42

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Why is this alternating sum involving Catalan numbers $\sum_{i=0}^{\lfloor t/2 \rfloor} (-1)^{i+1} \binom{t-i}{i} C_{t-i-1} = 0$ for all $t$?

answered Jan 18, 2023 at 4:35

4 votes

A binomial product sum that turns out to be 1

answered Feb 2, 2022 at 6:38

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Counting matrices of special types

answered Feb 25, 2019 at 17:32

4 votes

Cycle index of $(S_n \times S_n) \rtimes C_2$ acting on matrix indices by row/column permutation and transposition

answered Sep 11, 2018 at 15:32

4 votes

What is the number of achiral color patterns for a row of n colors containing k different colors?

answered Jan 30, 2018 at 6:06

4 votes

What (if anything) happened to Viennot's theory of Heaps of pieces?

answered Mar 22, 2017 at 18:13

4 votes

Unified framework for posets with order polynomial product formulas

answered Oct 6, 2019 at 5:31

4 votes

Cyclotomic polynomials in combinatorics

answered Jul 26, 2020 at 3:46

4 votes

A special type of generating function for Fibonacci

answered Jan 22, 2020 at 21:22

4 votes

residue calculation for rational function

answered Mar 11, 2021 at 3:01

4 votes

Integrality of a sequence formed by sums

answered Jul 25, 2021 at 17:50

4 votes

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$0,1$-matrices with $1$ in every row/column vs. all $0,1$-matrices

answered Oct 7, 2021 at 2:43

4 votes

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Explicit Expansion for Certain Product of homogeneous Polynomials

answered Nov 17, 2016 at 16:54

4 votes

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Generating function for Dyck Words

answered Mar 17, 2012 at 21:02

4 votes

Identifying factors of higher order in a determinant

answered Jan 29, 2012 at 20:05

4 votes

hypergeometric closed form for z=1/4,-1/3

answered Oct 20, 2011 at 14:26

3 votes

Zeros of "exponential" function

answered Dec 21, 2011 at 14:18

Stack Exchange Network

191 Answers

NE-Lattice paths from $(0,0)$ to $(n,n)$ with $k$ peaks

Logarithm of the hypergeometric function

Are there Prüfer sequences for rooted forests?

A hypergeometric identity related to Bessel functions

The number of Dyck paths of length $2n$ and height exactly $k$

Binomial coefficient congruence modulo $p^n$

Representing PSET as species

5 different ways to define the same family of integer sequences

$n$-th derivative of $\exp\left(-\frac{\lambda(x-\mu)^2}{2\mu^2x}\right)$

Unconventional types of induction

General case of the some $R$-recursions

$R$-recursion for the A307389

Is this a known symmetry of lattice paths?

Why is this alternating sum involving Catalan numbers $\sum_{i=0}^{\lfloor t/2 \rfloor} (-1)^{i+1} \binom{t-i}{i} C_{t-i-1} = 0$ for all $t$?

A binomial product sum that turns out to be 1

Counting matrices of special types

Cycle index of $(S_n \times S_n) \rtimes C_2$ acting on matrix indices by row/column permutation and transposition

What is the number of achiral color patterns for a row of n colors containing k different colors?

What (if anything) happened to Viennot's theory of Heaps of pieces?

Unified framework for posets with order polynomial product formulas

Cyclotomic polynomials in combinatorics

A special type of generating function for Fibonacci

residue calculation for rational function

Integrality of a sequence formed by sums

$0,1$-matrices with $1$ in every row/column vs. all $0,1$-matrices

Explicit Expansion for Certain Product of homogeneous Polynomials

Generating function for Dyck Words

Identifying factors of higher order in a determinant

hypergeometric closed form for z=1/4,-1/3

Zeros of "exponential" function