A131519 a(1) = 1, a(2) = 6, a(3) = 66, a(4) = 714, and a(n) = 11*a(n-1) - 24*a(n-3) for n >= 5.

1, 6, 66, 714, 7710, 83226, 898350, 9696810, 104667486, 1129781946, 12194877966, 131631637962, 1420833250878, 15336488688474, 165542216262126, 1786864380862314, 19287432460962078, 208188743880291834, 2247191437542514638, 24256207433904571146, 261821751919823278590

Offset

1,2

Links

G. C. Greubel, Table of n, a(n) for n = 1..950

Index entries for linear recurrences with constant coefficients, signature (11, 0, -24).

Formula

For n>4, a(n) = 11*a(n-1) - 24*a(n-3). - Max Alekseyev, Sep 29 2007

G.f.: x*(1-2*x)*(1-3*x-6*x^2)/(1-11*x+24*x^3). - R. J. Mathar, Nov 14 2007

Mathematica

LinearRecurrence[{11, 0, -24}, {1, 6, 66, 714}, 30] (* G. C. Greubel, Feb 14 2021 *)

Prog

(Sage)
def A131519_list(prec):
    P.<x> = PowerSeriesRing(ZZ, prec)
    return P( x*(1-2*x)*(1-3*x-6*x^2)/(1-11*x+24*x^3) ).list()
a=A131519_list(31); a[1:] # G. C. Greubel, Feb 14 2021
(Magma) I:=[6, 66, 714]; [1] cat [n le 3 select I[n] else 11*Self(n-1) -24*Self(n-3): n in [1..30]]; // G. C. Greubel, Feb 14 2021

Crossrefs

Previously this sequence was thought to represent what now is A354228.

Sequence in context: A186673 A213453 A186671 * A022024 A186666 A129554

Adjacent sequences: A131516 A131517 A131518 * A131520 A131521 A131522

Keyword

nonn

Author

Yasutoshi Kohmoto, Aug 15 2007, Oct 03 2007

Extensions

More terms from Max Alekseyev, Sep 29 2007

Edited by Max Alekseyev, Jul 18 2022

Status

approved