A202207 a(n) = 3*a(n-1) - a(n-2) + a(n-3) with a(0)=1, a(1)=2, a(2)=5.

1, 2, 5, 14, 39, 108, 299, 828, 2293, 6350, 17585, 48698, 134859, 373464, 1034231, 2864088, 7931497, 21964634, 60826493, 168446342, 466477167, 1291811652, 3577404131, 9906877908, 27435041245, 75975649958, 210398786537

Offset: 0

Author

Philippe Deléham, Dec 14 2011

Keywords

• easy
• nonn

Links

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

Crossrefs

Cf. A200752.

Programs

PARI

my(x='x+O('x^40)); Vec((1-x)/(1-3*x+x^2-x^3)) \\ Michel Marcus, Apr 10 2024

Formula

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

a(n) = A200752(n+3) - A200752(n+2). - R. J. Mathar, Dec 15 2011