OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (12,30,-12,-1).
FORMULA
a(n) is asymptotic to (1/8)*(7+2*sqrt(5))^n.
a(n) = 2 * A052208(n).
G.f.: 2*x*(x^2+1) / ((x^2-2*x-1)*(x^2+14*x-1)). - Colin Barker, Oct 19 2013
PROG
(PARI) a(n)=if(n<0, 0, contfracpnqn(vector(n, i, 1+(i>1)))[2, 1]*contfracpnqn(vector (2*n, i, 1+(i>1)))[2, 1])
(PARI) Vec(2*x*(x^2+1)/((x^2-2*x-1)*(x^2+14*x-1)) + O(x^100)) \\ Colin Barker, Oct 19 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Gary W. Adamson, Feb 01 2000
STATUS
approved