All Questions
Tagged with generating-functions polynomials
23 questions
0
votes
1
answer
59
views
Formula for $P(d) = \sum_{\sum_{i=1}^m k_i = d, k_i \in \mathbb{N}_+} \left( \prod_{i=1}^m k_i^{a_i} \right) $
Let $\mathbb{N}_+ = \{ 1, 2, \dots\} $. For a given sequence of elements $\{a_i \}_{1 \leq i \leq m} $in $ \mathbb{N}_+ $, we define
\begin{equation}
P(d) = \sum_{\sum_{i=1}^m k_i = d, k_i \in \...
- 89
2
votes
1
answer
310
views
Generating function for A300483 (related to Chebyshev polynomial of first kind)
Let $a(n)$ be A300483. Here
$$
a(n) = 2\int\limits_{t \geqslant 0}T_n\left(\frac{t+1}{2}\right)\exp(-t)\,dt.
$$
where $T_n(x)$ is $n$-th Chebyshev polynomial of first kind.
Let $b(n)$ be an integer ...
- 4,938
2
votes
5
answers
541
views
Finding $\sum_i x_i$ given $\{\sum_i x_i^{2n}\}_{n\in \mathbb{N}}$
Can we find $\sum_i x_i$ given $\{\sum_i x_i^{2n}\}_{n\in \mathbb{N}}$, assuming $\{x_i\}_{i\in\mathbb{N}}$ is a set of positive real numbers?
Perhaps an easier question is, can we find $\sum_i x_i$ ...
- 433
9
votes
2
answers
344
views
Counting $m\times n$ $\bigl({1\atop1}{1\atop0}\bigr)$-free $(0,1)$-matrices
Let $G_{m,n}$ denote the number of $m\times n$ $(0,1)$-matrices that avoid the submatrix $\bigl({1\atop1}{1\atop0}\bigr)$. (Submatrices need not be contiguous.) Here are some small values (not yet on ...
- 667
2
votes
1
answer
216
views
Slicing bivariate exponential generating functions on x and y
Let $F(x, y) = e^{y D(x)}$ be a generating function for sets of objects enumerated by $D(x)$ that also keeps track of the number of sets (enumerated by the variable $y$, while $x$ enumerates the total ...
- 1,171
1
vote
2
answers
462
views
Closed formula for Hermite polynomials
Hermite polynomials $H_k(x), x \in \mathbb{R}, k \in \mathbb{N}$ are defined by the formula
$$
H_k(x)=(-1)^k e^{x^2} \frac{d^k}{d x^k}\left(e^{-x^2}\right) .
$$
Each $H_k(x)$ is a polynomial of exact ...
- 521
1
vote
1
answer
122
views
How to interpret this result modulo $(y-1)^{n+1}$?
I recently discovered that the following identity is true:
$$
\boxed{\frac{\partial^{n+1}}{\partial x^{n+1}}\left(\frac{(xy-1)^n}{n!} \log \frac{1}{1-x}\right) \equiv \frac{y^{n+1}}{1-xy} \pmod{(y-1)^{...
- 1,171
0
votes
0
answers
84
views
Arithmetic triangles and unimodality of its rows
Let's consider the sequence of coefficients of $\prod_{i}\frac {1-x^{d_i}} {1-x}$, where $d_i$ is a monotonically increasing nonnegative integer sequence.
How to prove that the coefficients form an ...
2
votes
0
answers
117
views
A multi-variable "Fibonacci polynomial"?
There is a tremendous literature on the Fibonacci sequence, including its polynomial analogue $F_{-1}=0, F_0=1$ and
$$F_n(x)=xF_{n-1}(x)+F_{n-2} \qquad \text{for $n\geq1$}.$$
What I have found is the ...
- 43.2k
3
votes
1
answer
281
views
Analytic expression for the coefficient of a multivariate polynomial
Does there exist some method for finding an analytic expression for the coefficient of $z_1^kz_2^kz_3^k$ in:
$$[(1+z_1)(1+z_2)(1+z_3)(1+z_1z_2)(1+z_1z_3)(1+z_2z_3)(1+z_1z_2z_3)]^{k}$$
or is it ...
- 1,000
6
votes
0
answers
207
views
Parameter independence of Stanley's "content formula". Why?
For a cell $\square$ in the Young diagram of a partition $\lambda$, let $h_{\square}$ and $c_{\square}$ denote the hook length and content of $\square$, respectively.
R. Stanley remarked following ...
- 43.2k
3
votes
1
answer
272
views
Generating function for parity in hooks
Let $\lambda\vdash n$ denote an integer partition of $n$ and $\frak{H}_{\lambda}$ be the multiset of hook lengths of $\lambda$. Further, let $o(\lambda)=\#$ of odd entries and $e(\lambda)=\#$ of even ...
- 43.2k
1
vote
1
answer
233
views
Closed-form formula for a multivariate polynomial
Counting certain walks in threshold graphs, I came to the following independent problem. Assume that $x_1,\dots,x_a$ are independent variables and for $k\geq 2$ let
$$
P_k(x_1,\dots,x_a)=\sum_{(i_1,\...
0
votes
1
answer
250
views
If the coefficient of the polynomial positive
I want to know what is following sum coefficient looks like. We sum over all integers $p$, $q$ also we put the condition that $q$ is even. Also, it should depend on the parity of $k$
$$\bar{S}(k)=\...
- 685
4
votes
1
answer
287
views
A 2nd order recursion with polynomial coefficients
I'm hoping to find "exact" an solution to the following simple recursion:
$q_m(j+1) = m \cdot q_m(j) + j(j+m)\cdot q_m(j-1)$
with initial data $q_m(0) = 1$, $q_m(1)=m$, where $m \geq 0$ is an ...
6
votes
3
answers
372
views
Second order recurrence relation for third order polynomial root
Consider this recurrence relation:
$$
\begin{eqnarray*}
f_0&=&1\\
f_n&=&
\sum_{m=0}^{n-1} \frac{\left(\frac{m+3}{2}\right)_{m-1}}{\left(\frac{m+2}{2}\right)_m} f_{n-m-1} f_m\ \ \ \...
- 237
1
vote
0
answers
101
views
Construct generating functions of series of palindromic polynomials
I have a problem that is generating a series ($d=2,4,\ldots,20,\ldots$) of pairs of $4 d$-degree palindromic (self-reciprocal) polynomials.
The first three members ($d=2,4,6$) of the first pair are:
\...
- 723
1
vote
0
answers
196
views
A question about integer representation as a sum of two coprime integers
It is easy to see that every natural number $n$ can be written in a unique way $n = a+b$ where $gcd(a,b)=1$, $b>a$ and $b-a$ is minimal with this property. For instance if $n$ is odd the ...
user6671
4
votes
1
answer
231
views
Product of polynomial coefficients of a recurrence
A recurrence is given by
$f[0]=2x$, $f[1]=3x^3-x^2+x+1$,
$$
f[n]=(x^{2^n}+1)f[n-1]+(x^{2^n}+1)(x^{2^n-1}+1)
$$
How does the PRODUCT of the nonzero coefficients of $f[n]$ scale with $n$?
3
votes
0
answers
312
views
Enumerating a class of polynomials
How many equivalence classes of $\Bbb F_2[x,y]$ polynomials with $x$ degree $n_x$ and $y$ degree $n_y$ are there such that each $y^i$ coefficient (polynomial in $\Bbb Z[x]$) is distinct and $x^i$ ...
user76479
2
votes
0
answers
193
views
Hilbert series of the weight 0 sub-algebra of the algebra of functions on GL(N)
Let $A$ be the algebra of polynomials in $N^2$ variables $x^i_j$, $i,j=1,\dots,N$. It is $\mathbb{Z}^N$ graded, with $\text{weight}(x^i_j)=e_i-e_j$. Here $(e_1,\dots,e_n)$ is the standard basis of $\...
- 169
1
vote
1
answer
304
views
Truncated sums of symmetric polynomials; reference request for an algebraic derivation
EDIT: This is a case of being too wrapped up in a formulation
($e_j,p_i,$ and the like) to try something simple. It did not
occur to me to pull exp to the outside in the weeks I have
stared at this. ...
- 13k
4
votes
0
answers
221
views
probabilistic terminology for polynomials with positive coefficients
Given a polynomial $P(x) = p_0 + p_1 x + p_2 x^2 + ... + p_n x^n$ with non-negative coefficients, is there a standard name for (the function of $p_1,...,p_n$ equal to) the variance of an integer-...
- 19.7k