A131505 n, -1, n, 2n+2.

0, -1, 0, 2, 1, -1, 1, 4, 2, -1, 2, 6, 3, -1, 3, 8, 4, -1, 4, 10, 5, -1, 5, 12, 6, -1, 6, 14, 7, -1, 7, 16, 8, -1, 8, 18, 9, -1, 9, 20, 10, -1, 10, 22, 11, -1, 11, 24, 12, -1, 12, 26, 13, -1, 13, 28, 14, -1, 14, 30, 15, -1, 15, 32, 16, -1, 16, 34, 17, -1, 17, 36, 18, -1, 18, 38, 19, -1, 19, 40, 20, -1, 20, 42, 21, -1, 21, 44, 22, -1, 22, 46, 23

Offset

0,4

Comments

Based on A129819 (the first with 0 0).

Links

Table of n, a(n) for n=0..92.

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

Formula

G.f.: (-x*(1 - 2*x + x^2 - x^3))/(1 - x + x^2 - x^3)^2. - Georg Fischer, May 05 2021

Maple

seq(coeff(series( (-x*(1 - 2*x + x^2 - x^3))/(1 - x + x^2 - x^3)^2, x, n+1), x, n), n = 0..40); # Georg Fischer, May 05 2021

Mathematica

Flatten[Table[{n, -1, n, 2n+2}, {n, 0, 30}]] (* Harvey P. Dale, Nov 15 2011 *)

Crossrefs

Sequence in context: A294897 A252733 A181876 * A100092 A131508 A305502

Adjacent sequences: A131502 A131503 A131504 * A131506 A131507 A131508

Keyword

sign,easy

Author

Paul Curtz, Aug 13 2007

Status

approved