Newbetuts

If $P(x)=\sum_{i=0}^da_i\left(\prod_{j=i}^{d+i-1}(x+j)\right)$ is linear, what is its constant term?

Analyzing the Coefficient of a generating function and its asymptotic

sign reversing involution proof of a combinatorial identity

Bijection = bijection + bijection on symmetric integer intervals

Secret santa problem

Combinatorial proof that $\sum_{k=0}^n \binom{n}{k} \frac{(-1)^k}{(k+1)^2} = \frac{H_{n+1}}{n+1}$

the number of positive-integer solutions that satisfy $x_1\cdot x_2\cdot x_3\cdot x_4=1,000,000$?

How to simplify this combinatorial sum

Can we count odd and even derangements nicely without taking a determinant?

Find $\sum_{i\in\mathbb{N}}(n-2i)^k\binom{n}{2i+1}$

In how many ways can you colorize the vertices of a grid with 4 colors so that every unit-square vertices are all of a different color?

An efficient way to check the coefficient of $x_1 x_2...x_n$ in the product of $m$ polynomials

Several rectangles cover the unit square. Can I find a disjoint set of them whose area is at least $1/4$?

Error in solution of Peter Winkler "red and blue dice" puzzle?

What is the probability that $\pi(x) + x$ is injective?

Is there a “spanning simplex” method to calculate homology of low dimensional simplicial complexes?

Distinguishable painted prisms with six colors (repetition allowed)

New posts in combinatorics

Help with binomial identity

Divide $1^2,2^2..,81^2$ numbers into 3 groups.

Picking balls from urns.

If $P(x)=\sum_{i=0}^da_i\left(\prod_{j=i}^{d+i-1}(x+j)\right)$ is linear, what is its constant term?

Analyzing the Coefficient of a generating function and its asymptotic

sign reversing involution proof of a combinatorial identity

Bijection = bijection + bijection on symmetric integer intervals

Secret santa problem

Combinatorial proof that $\sum_{k=0}^n \binom{n}{k} \frac{(-1)^k}{(k+1)^2} = \frac{H_{n+1}}{n+1}$

the number of positive-integer solutions that satisfy $x_1\cdot x_2\cdot x_3\cdot x_4=1,000,000$?

How to simplify this combinatorial sum

Can we count odd and even derangements nicely without taking a determinant?

Find $\sum_{i\in\mathbb{N}}(n-2i)^k\binom{n}{2i+1}$

In how many ways can you colorize the vertices of a grid with 4 colors so that every unit-square vertices are all of a different color?

An efficient way to check the coefficient of $x_1 x_2...x_n$ in the product of $m$ polynomials

Several rectangles cover the unit square. Can I find a disjoint set of them whose area is at least $1/4$?

Error in solution of Peter Winkler "red and blue dice" puzzle?

What is the probability that $\pi(x) + x$ is injective?

Is there a “spanning simplex” method to calculate homology of low dimensional simplicial complexes?

Distinguishable painted prisms with six colors (repetition allowed)