A078071 Expansion of (1-x)/(1+2*x+2*x^2+2*x^3).

1, -3, 4, -4, 6, -12, 20, -28, 40, -64, 104, -160, 240, -368, 576, -896, 1376, -2112, 3264, -5056, 7808, -12032, 18560, -28672, 44288, -68352, 105472, -162816, 251392, -388096, 599040, -924672, 1427456, -2203648, 3401728, -5251072, 8105984, -12513280, 19316736, -29818880, 46030848

Offset: 0

Author

N. J. A. Sloane, Nov 17 2002

Keywords

• sign
• easy

Links

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

Crossrefs

First differences of A077993.

Programs

PARI

Vec((1-x)/(1+2*x+2*x^2+2*x^3) + O(x^50)) \\ Jinyuan Wang, Apr 07 2020

Formula

a(0) = 1, a(1) = -3, a(2) = 4, a(n) = -2*(a(n-1) + a(n-2) + a(n-3)) for n > 2. - Jinyuan Wang, Apr 07 2020