OFFSET
0,2
LINKS
FORMULA
G.f.: (1+x)/(1-x-8*x^2).
a(n) = Sum_{k=0..n+1} A122950(n+1,k)*7^(n+1-k). - Philippe Deléham, Jan 08 2008
a(n) = ((11+sqrt(33))/22)*(1/2 + (1/2)*sqrt(33))^n + ((11-sqrt(33))/22)*(1/2 - (1/2)*sqrt(33))^n. - Richard Choulet, Nov 20 2008
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Philippe Deléham, Jan 03 2008
STATUS
approved