A092352 - OEIS

A092352

G.f.: (1+3*x^3)/((1-x)^2*(1-x^3)^2).

1, 2, 3, 9, 15, 21, 36, 51, 66, 94, 122, 150, 195, 240, 285, 351, 417, 483, 574, 665, 756, 876, 996, 1116, 1269, 1422, 1575, 1765, 1955, 2145, 2376, 2607, 2838, 3114, 3390, 3666, 3991, 4316, 4641, 5019, 5397, 5775, 6210, 6645, 7080, 7576, 8072, 8568, 9129, 9690

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..49.

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

Index entries for linear recurrences with constant coefficients, signature (2,-1,2,-4,2,-1,2,-1).

FORMULA

a(n) ~ 2/27*n^3. - Ralf Stephan, Apr 29 2014

MATHEMATICA

CoefficientList[Series[(1+3x^3)/((1-x)^2(1-x^3)^2), {x, 0, 80}], x] (* or *) LinearRecurrence[ {2, -1, 2, -4, 2, -1, 2, -1}, {1, 2, 3, 9, 15, 21, 36, 51}, 80] (* Harvey P. Dale, May 27 2022 *)

CROSSREFS

Sequence in context: A056702 A294126 A091361 * A061933 A251239 A124881

Adjacent sequences: A092349 A092350 A092351 * A092353 A092354 A092355

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Mar 20 2004

STATUS

approved