OFFSET
0,2
FORMULA
G.f.: A(x) = (1-x-x^2)/(1-x)^2 + x*A(x)^2.
EXAMPLE
a(3)=-1+1+6+5=11, a(4)=-2-2+6+20+14=36, a(5)=-3-6-4+30+70+42=129.
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jul 24 2003
STATUS
approved