A189738 a(1)=3, a(2)=4, a(n) = 3*a(n-1) + 4*a(n-2).

3, 4, 24, 88, 360, 1432, 5736, 22936, 91752, 367000, 1468008, 5872024, 23488104, 93952408, 375809640, 1503238552, 6012954216, 24051816856, 96207267432, 384829069720, 1539316278888, 6157265115544, 24629060462184, 98516241848728, 394064967394920

Offset: 1

Author

Harvey P. Dale, Apr 26 2011

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..100
• Index entries for linear recurrences with constant coefficients, signature (3,4).

Crossrefs

Cf. A201455.

Programs

Mathematica

LinearRecurrence[{3,4},{3,4},40]

Maxima

a[1]:3$ a[2]:4$ a[n]:=3*a[n-1]+4*a[n-2]$ makelist(a[n], n, 1, 25); /* Bruno Berselli, May 24 2011 */

PARI

a(n)=7<<(2*n)\/20-2*(-1)^n \\ Charles R Greathouse IV, Jul 15 2011

Formula

G.f.: x*(3-5*x)/(1-3*x-4*x^2). - Bruno Berselli, May 24 2011