cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A214407 Triangle read by rows. The coefficients in ascending order of x^i of the polynomials p{0}(x) = 1 and p{n}(x) = Sum_{k=0..n-1; k even} binomial(n, k) * p{k}(0)*(1 - n%2 + x^(n - k)).

Original entry on oeis.org

1, 0, 1, 1, 0, 1, 0, 3, 0, 1, 7, 0, 6, 0, 1, 0, 35, 0, 10, 0, 1, 121, 0, 105, 0, 15, 0, 1, 0, 847, 0, 245, 0, 21, 0, 1, 3907, 0, 3388, 0, 490, 0, 28, 0, 1, 0, 35163, 0, 10164, 0, 882, 0, 36, 0, 1, 202741, 0, 175815, 0, 25410, 0, 1470, 0, 45, 0, 1, 0
Offset: 0

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Author

Peter Luschny, Jul 16 2012

Keywords

Comments

Matrix inverse of a signed variant of A119467.

Examples

			1
0, 1
1, 0, 1
0, 3, 0, 1
7, 0, 6, 0, 1
0, 35, 0, 10, 0, 1
121, 0, 105, 0, 15, 0, 1
0, 847, 0, 245, 0, 21, 0, 1
3907, 0, 3388, 0, 490, 0, 28, 0, 1
		

Crossrefs

Cf. A119467, A327034 (row sums), A094088 (column 0).

Programs

  • Sage
    @CachedFunction
    def A214407_poly(n, x) :
        return 1 if n==0 else add(A214407_poly(k, 0)*binomial(n, k)*(x^(n-k)+1-n%2) for k in range(n)[::2])
    def A214407_row(n) :
        R = PolynomialRing(ZZ, 'x')
        return R(A214407_poly(n,x)).coeffs()
    for n in (0..8) : A214407_row(n)

Formula

T(n, k) = n! * [y^k] [x^n] (exp(x * y) / (2 - cosh(x))). - Peter Luschny, May 06 2023