OFFSET
0,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,4).
FORMULA
G.f.: (21*x + 12)/(-4*x^2 + 1).
a(n) = -(9/4)*sqrt(2)*(1/2)^(-1/2*(-1)^n)*(-2)^n + (33/4)*2^n*sqrt(2)*(1/2)^(-(1/2)*(-1)^n) - Alexander R. Povolotsky, Apr 25 2008
a(n) = 3*A133600(n+2) - R. J. Mathar, Jun 08 2016
MATHEMATICA
LinearRecurrence[{0, 4}, {12, 21}, 50] (* G. C. Greubel, Feb 23 2017 *)
PROG
(PARI) x='x + O('x^50); Vec((21*x + 12)/(-4*x^2 + 1)) \\ G. C. Greubel, Feb 23 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Apr 22 2008
STATUS
approved