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.

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A383568 Expansion of 1/sqrt((1-x^5)^2 - 4*x^2).

Original entry on oeis.org

1, 0, 2, 0, 6, 1, 20, 6, 70, 30, 253, 140, 936, 630, 3522, 2773, 13430, 12032, 51770, 51690, 201389, 220470, 789546, 935330, 3116416, 3951949, 12373910, 16645398, 49389050, 69938416, 198048409, 293296470, 797461358, 1228136090, 3222960100, 5136602753
Offset: 0

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Author

Seiichi Manyama, Apr 30 2025

Keywords

Comments

Number of lattice paths from (0,0) to (n,n) using steps (2,0),(0,2),(5,5).
Diagonal of the rational function 1 / (1 - x^2 - y^2 - x^5*y^5).
Diagonal of the rational function 1 / ((1-x^2*y)*(1-x^3*y^4) - y).

Crossrefs

Main diagonal of A383567.

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec(1/sqrt((1-x^5)^2-4*x^2))
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