A118408 Row sums of triangle A118407.

1, 1, -1, 1, 1, -1, 3, -3, 1, 7, -13, 13, 1, -25, 51, -51, 1, 103, -205, 205, 1, -409, 819, -819, 1, 1639, -3277, 3277, 1, -6553, 13107, -13107, 1, 26215, -52429, 52429, 1, -104857, 209715, -209715, 1, 419431, -838861, 838861, 1, -1677721, 3355443, -3355443, 1, 6710887, -13421773, 13421773, 1

Offset: 0

Author

Paul D. Hanna, Apr 27 2006

Keywords

• sign

Links

• Index entries for linear recurrences with constant coefficients, signature (-1, -1, 1, 0, 2).

Crossrefs

Cf. A118407 (triangle), A118409 (unsigned row sums).

Programs

PARI

{a(n)=polcoeff((1+x)^2/(1+x^2)/(1+2*x+2*x^2)/(1-x+x*O(x^n)),n)}

Formula

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