A101604 a(n) = 2*a(n-1) + 5*a(n-2) + 2*a(n-3).

1, 2, 9, 30, 109, 386, 1377, 4902, 17461, 62186, 221481, 788814, 2809405, 10005842, 35636337, 126920694, 452034757, 1609945658, 5733906489, 20421610782, 72732645325, 259041157538, 922588763265, 3285848604870, 11702723341141

Offset

0,2

Comments

Transform of 2^n under Riordan array A101603.

Links

Table of n, a(n) for n=0..24.

Index entries for linear recurrences with constant coefficients, signature (2,5,2).

Formula

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

a(n) = (3/4 + sqrt(17)/4)^n*(1/4 + 7*sqrt(17)/68) + (1/4 - 7*sqrt(17)/68)*(3/4 - sqrt(17)/4)^n + (-1)^n/2;

a(n) = (A007483(n) + (-1)^n)/2. - R. J. Mathar, Sep 21 2012

Crossrefs

Cf. A007483, A101603.

Sequence in context: A201164 A289901 A261330 * A234007 A203365 A181954

Adjacent sequences: A101601 A101602 A101603 * A101605 A101606 A101607

Keyword

easy,nonn

Author

Paul Barry, Dec 08 2004

Status

approved