A109266 Diagonal sums of Riordan array (1-x-x^2,x(1-x)).

1, -1, 0, -2, 1, -2, 3, -3, 5, -6, 8, -11, 14, -19, 25, -33, 44, -58, 77, -102, 135, -179, 237, -314, 416, -551, 730, -967, 1281, -1697, 2248, -2978, 3945, -5226, 6923, -9171, 12149, -16094, 21320, -28243, 37414, -49563, 65657, -86977, 115220, -152634, 202197, -267854, 354831, -470051, 622685, -824882

Offset: 0

Author

Paul Barry, Jun 24 2005

Keywords

• easy
• sign

Links

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

Formula

G.f.: (1-x-x^2)/(1-x^2+x^3); a(n)=a(n-2)-a(n-3).