OFFSET
0,2
FORMULA
a(n)= (n+2)*((3*n+1)*F(n-1)/2+(2*n+1)*F(n)), with F(n) := A000045(n) (Fibonacci).
G.f.: (1+4*x-x^2)*(1+2*x)/(1-x-x^2)^3.
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Feb 15 2002
STATUS
approved