A078059 Expansion of (1-x)/(1+2*x-x^2+2*x^3).

1, -3, 7, -19, 51, -135, 359, -955, 2539, -6751, 17951, -47731, 126915, -337463, 897303, -2385899, 6344027, -16868559, 44852943, -119262499, 317115059, -843198503, 2242037063, -5961502747, 15851439563, -42148455999, 112071357055, -297994049235, 792356367523, -2106849498391

Offset: 0

Author

N. J. A. Sloane, Nov 17 2002

Keywords

• sign
• easy

Links

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

Programs

PARI

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

Formula

a(0) = 1, a(1) = -3, a(2) = 7, a(n) = -2*a(n-1) + a(n-2) - 2*a(n-3) for n > 2. - Jinyuan Wang, Apr 07 2020

a(n) = A077987(n)-A077987(n-1). - R. J. Mathar, Mar 19 2025