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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A265055 Expansion of b(2)*b(4)*b(6)/(x^8-x^4-x+1), where b(k) = (1-x^k)/(1-x).

Original entry on oeis.org

1, 4, 9, 16, 25, 37, 53, 74, 101, 135, 179, 237, 313, 411, 537, 700, 912, 1188, 1546, 2009, 2608, 3385, 4394, 5703, 7399, 9596, 12444, 16138, 20929, 27140, 35190, 45625, 59155, 76699, 99445, 128932, 167158, 216717, 280972, 364279, 472282, 612300, 793827, 1029174, 1334298
Offset: 0

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Author

N. J. A. Sloane, Dec 27 2015

Keywords

Comments

This is the Poincaré series [or Poincare series] for the quasi-Lannér diagram QL4_1 - see Tables 7.6, 7.7 and 7.8 in Maxim Chapovalov, Dimitry Leites and Rafael Stekolshchik (2009), or equivalently Tables 5 and 6 in the shorter version, Maxim Chapovalov, Dimitry Leites and Rafael Stekolshchik (2010).

Crossrefs

Programs

  • Magma
    /* By definition: */ m:=50; R:=PowerSeriesRing(Integers(), m); b:=func; Coefficients(R!(b(2)*b(4)*b(6)/(x^8-x^4-x+1))); // Bruno Berselli, Dec 28 2015
  • Mathematica
    Join[{1, 4}, LinearRecurrence[{1, 0, 0, 1, 0, 0, 0, -1}, {9, 16, 25, 37, 53, 74, 101, 135}, 50]] (* Jean-François Alcover, Jan 08 2019 *)

Formula

G.f.: (1 + x^2)*(1 - x + x^2)*(1 + x + x^2)*(1 + x)^3/((1 - x)*(1 - x^4 - x^5 - x^6 - x^7)). [Bruno Berselli, Dec 28 2015]
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