A008618 - OEIS

A008618

Expansion of 1/((1-x^2)(1-x^9)).

1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 3, 4, 3, 4, 3, 4, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 4, 5, 4, 5, 4

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OFFSET

0,19

REFERENCES

D. J. Benson, Polynomial Invariants of Finite Groups, Cambridge, 1993, p. 100.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

D. J. Benson, Polynomial Invariants of Finite Groups, Cambridge, 1993, p. 100.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 215

Index entries for linear recurrences with constant coefficients, signature (0, 1, 0, 0, 0, 0, 0, 0, 1, 0, -1).

FORMULA

a(n) = floor((2*n+27+9*(-1)^n)/36). - Tani Akinari, May 19 2014

MATHEMATICA

CoefficientList[Series[1 / ((1 - x^2) (1 - x^9)), {x, 0, 100}], x] (* Vincenzo Librandi, Jun 22 2013 *)

PROG

(PARI) a(n)=floor((2*n+27+9*(-1)^n)/36) \\ Tani Akinari, May 19 2014

CROSSREFS

Sequence in context: A298475 A175096 A111627 * A339368 A225572 A318471

Adjacent sequences: A008615 A008616 A008617 * A008619 A008620 A008621

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Typo in name fixed by Vincenzo Librandi, Jun 22 2013

STATUS

approved