A133665 a(n) = a(n-1) - 9*a(n-2), a(0) = 1, a(1) = 3.

1, 3, -6, -33, 21, 318, 129, -2733, -3894, 20703, 55749, -130578, -632319, 542883, 6233754, 1347807, -54755979, -66886242, 425917569, 1027893747, -2805364374, -12056408097, 13191871269, 121699544142, 2972702721, -1092323194557, -1119077519046, 8711831231967

Offset: 0

Author

Philippe Deléham, Dec 28 2007

Keywords

• sign
• easy

Links

• Harvey P. Dale, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (1,-9).

Crossrefs

Cf. A133607.

Programs

Mathematica

LinearRecurrence[{1,-9},{1,3},40] (* Harvey P. Dale, Apr 21 2019 *)

PARI

Vec((1+2*x)/(1-x+9*x^2) + O(x^30)) \\ Jinyuan Wang, Apr 09 2020

Formula

G.f.: (1+2*x)/(1-x+9*x^2).

a(n) = Sum_{k=0..n} A133607(n,k)*3^k. - Philippe Deléham, Dec 29 2007

Extensions

Corrected and extended by Harvey P. Dale, Apr 21 2019