A091702 Column 0 of triangle A091700.

1, 2, 7, 23, 78, 264, 895, 3034, 10286, 34872, 118225, 400813, 1358859, 4606881, 15618510, 52950761, 179516682, 608607667, 2063336333, 6995240208, 23715661274, 80402183905, 272584057514, 924129977596, 3133038018732, 10621803712455, 36010643162123

Offset

0,2

Links

Table of n, a(n) for n=0..26.

Index entries for linear recurrences with constant coefficients, signature (3,2,-2,-1).

Formula

G.f.: (1-x-x^2)/(1-3x-2x^2+2x^3+x^4).

From Philippe Deléham, May 04 2023: (Start)

a(n) = 3*a(n-1) + 2*a(n-2) - 2*a(n-3) - a(n-4), for n>3.

a(n) = M^n [1, 1] where M = [2, 1, 1, 1 ; 1, 1, 1, 0 ; 1, 1, 0, 0 ; 1, 0, 0, 0 ] . (End)

Crossrefs

Cf. A091700.

Sequence in context: A292235 A292236 A292087 * A274104 A068593 A198944

Adjacent sequences: A091699 A091700 A091701 * A091703 A091704 A091705

Keyword

nonn,easy

Author

Christian G. Bower, Jan 29 2004

Status

approved