A261054 Expansion of ( 2+x-x^2+x^3 ) / (1-x^2-x)^3 .

2, 7, 20, 51, 118, 260, 548, 1121, 2236, 4373, 8412, 15960, 29926, 55547, 102196, 186567, 338258, 609532, 1092328, 1947829, 3457724, 6112873, 10766328, 18896880, 33062090, 57675631, 100338836, 174117915, 301432558, 520686644, 897559340, 1544207369, 2651881468, 4546263293, 7781245524

Offset: 0

Author

R. J. Mathar, Aug 08 2015

Keywords

• nonn
• easy

Comments

Third column of A234713.

Links

• Index entries for linear recurrences with constant coefficients, signature (3,0,-5,0,3,1).

Crossrefs

Cf. A234713.

Programs

Mathematica

LinearRecurrence[{3,0,-5,0,3,1},{2,7,20,51,118,260},40] (* Harvey P. Dale, Aug 10 2024 *)

Formula

a(n) = 2*A001628(n) +A001628(n-1) -A001628(n-2) +A001628(n-3).