List questions from combinatorial-proofs

Published on 27 Mar 2026 - 2:37

46

Views

Find how many n-digit positive integers using the digits 1, 2, and 3, such that no two 1's are next to each other.

Published on 09 Jan 2024 - 5:33

113

Views

Number of permutations such that each number is either greater than all the numbers to its left or less than all the numbers to its right.

Published on 12 Jan 2024 - 3:32

36

Views

Connecting generating functions for binomial and negative binomial distributions

Published on 17 Jan 2024 - 12:16

133

Views

Combinatorial proof of $ \binom{n+1}{k} = \binom{n}{k-1} + \binom{n}{k}. $

Published on 21 Jan 2024 - 6:19

130

Views

Is there a simpler proof for the following identity: $\sum_{n=0}^x \frac{(n+x)!}{n!2^n} = x!2^x$

Published on 22 Jan 2024 - 17:39

58

Views

Triangulation in Monsky's Theorem

Published on 26 Mar 2026 - 6:10

253

Views

Game of cards and divisors

Published on 25 Jan 2024 - 15:43

56

Views

Linear independence of binary vectors

Published on 25 Jan 2024 - 20:20

140

Views

Probability of ballot ending in a tie

Published on 30 Jan 2024 - 11:12

38

Views

Seeking combinatorial proof for an Identity involving $2^{2n}$ and a sum of binomial coefficients

Published on 30 Jan 2024 - 12:40

87

Views

Tic-tac-toe possible grids

Published on 27 Mar 2026 - 6:38

49

Views

Rewriting a sum over permutations

Published on 07 Feb 2024 - 22:24

91

Views

Prove that there are $n! - (n-1)(n-1)!$ ways to arrange $n$ objects in a circular arrangement.

Published on 19 Feb 2024 - 8:32

99

Views

Story proofs in Combinatorics/Probability

Published on 19 Feb 2024 - 14:57

List Question

How to prove that the following conclusion is true?

Find how many n-digit positive integers using the digits 1, 2, and 3, such that no two 1's are next to each other.

Number of permutations such that each number is either greater than all the numbers to its left or less than all the numbers to its right.

Connecting generating functions for binomial and negative binomial distributions

Combinatorial proof of $ \binom{n+1}{k} = \binom{n}{k-1} + \binom{n}{k}. $

Is there a simpler proof for the following identity: $\sum_{n=0}^x \frac{(n+x)!}{n!2^n} = x!2^x$

Triangulation in Monsky's Theorem

Game of cards and divisors

Linear independence of binary vectors

Probability of ballot ending in a tie

Seeking combinatorial proof for an Identity involving $2^{2n}$ and a sum of binomial coefficients

Tic-tac-toe possible grids

Rewriting a sum over permutations

Prove that there are $n! - (n-1)(n-1)!$ ways to arrange $n$ objects in a circular arrangement.

Story proofs in Combinatorics/Probability

Trending Questions

Popular # Hahtags

Popular Questions