OFFSET
0,1
COMMENTS
The o.g.f. S(x) for A001003 (Schroeder II) satisfies 2*S^2(x) + (1+x)*S(x) + x = 0.
LINKS
FORMULA
G.f.: x*(1-2*x)/(1-x).
a(0)=0,a(1)=1, a(n)=-1, n>=2.
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Wolfdieter Lang, Nov 13 2007
STATUS
approved