OFFSET
0,4
FORMULA
G.f.: 1/(1-x) = Sum_{n>=0} a(n)*x^n*(1+x)^(2^n).
PROG
(PARI) {a(n)=local(M=matrix(n+1, n+1, r, c, binomial(2^(c-1), r-c))); sum(k=0, n, (M^-1)[n+1, k+1])}
CROSSREFS
KEYWORD
sign
AUTHOR
Paul D. Hanna, Jan 01 2008
STATUS
approved