A096750 Expansion of (1-x+x^2)/(1-2x+2x^2-x^3-x^4).

1, 1, 1, 1, 2, 4, 6, 7, 8, 12, 21, 33, 44, 55, 76, 119, 185, 263, 351, 480, 706, 1066, 1551, 2156, 2982, 4269, 6281, 9162, 13013, 18252, 25921, 37513, 54449, 78045, 110626, 157124, 225490, 325403, 467576, 666960, 949661, 1358381, 1951976, 2803811

Offset: 0

Author

Paul Barry, Jul 07 2004

Keywords

• nonn
• easy

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (2,-2,1,1).

Crossrefs

Cf. A003522.

Programs

Mathematica

CoefficientList[Series[(1-x+x^2)/(1-2x+2x^2-x^3-x^4),{x,0,50}],x] (* or *) LinearRecurrence[ {2,-2,1,1},{1,1,1,1},50] (* Harvey P. Dale, Jun 16 2024 *)

Formula

a(n) = 2*a(n-1)-2*a(n-2)+a(n-3)+a(n-4).