OFFSET
1,1
LINKS
FORMULA
G.f.: x*(2+x+2*x^2) / ( (x-1)*(6*x-1)*(1+x+x^2) ). - R. J. Mathar, Apr 27 2015
PROG
(PARI) a(n)=([0, 1, 0, 0; 0, 0, 1, 0; 0, 0, 0, 1; -6, 1, 0, 6]^(n-1)*[2; 13; 80; 482])[1, 1] \\ Charles R Greathouse IV, Feb 13 2017
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved