A092533 - OEIS

A092533

G.f.: (1+x^8)/((1-x)*(1-x^4)).

1, 1, 1, 1, 2, 2, 2, 2, 4, 4, 4, 4, 6, 6, 6, 6, 8, 8, 8, 8, 10, 10, 10, 10, 12, 12, 12, 12, 14, 14, 14, 14, 16, 16, 16, 16, 18, 18, 18, 18, 20, 20, 20, 20, 22, 22, 22, 22, 24, 24, 24, 24, 26, 26, 26, 26, 28, 28, 28, 28, 30, 30, 30, 30, 32, 32, 32, 32, 34, 34, 34, 34, 36, 36, 36, 36, 38, 38

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OFFSET

0,5

LINKS

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

G. Nebe, E. M. Rains and N. J. A. Sloane, Self-Dual Codes and Invariant Theory, Springer, Berlin, 2006.

Index entries for Molien series

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

FORMULA

a(n) = 1 for n<4, a(n) = 2*floor(n/4) for n>=4. - Ralf Stephan, Apr 29 2014

MATHEMATICA

CoefficientList[Series[(1+x^8)/((1-x)(1-x^4)), {x, 0, 100}], x] (* or *) Join[{1, 1, 1, 1}, LinearRecurrence[{1, 0, 0, 1, -1}, {2, 2, 2, 2, 4}, 80]] (* Harvey P. Dale, Jul 25 2014 *)

PROG

(Magma) I:=[1, 1, 1, 1, 2, 2, 2, 2, 4]; [n le 9 select I[n] else Self(n-1)+Self(n-4)-Self(n-5): n in [1..30]]; // Vincenzo Librandi, Jul 25 2014

CROSSREFS

Sequence in context: A113452 A364932 A122461 * A092532 A073504 A092508

Adjacent sequences: A092530 A092531 A092532 * A092534 A092535 A092536

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Apr 08 2004

STATUS

approved