OFFSET
0,4
COMMENTS
EXAMPLE
G.f.: A(x) = 1 + x + x^2 + 3*x^3 + 6*x^4 + 33*x^5 + 79*x^6 + 661*x^7 +...
Related expansions.
A(x) = B(x*A(x)) where B(x) = A(x/B(x)) is the g.f. of A184506:
B(x) = 1 + x + 2*x^3 - 3*x^4 + 27*x^5 - 91*x^6 + 723*x^7 -+...
Also, A(x) = F(x*A(x)^2) where F(x) = A(x/F(x)^2) is the g.f. of A184507:
F(x) = 1 + x - x^2 + 4*x^3 - 16*x^4 + 86*x^5 - 482*x^6 + 3074*x^7 +...
PROG
(PARI) {a(n)=local(A=1, F=1+x+x*O(x^n)); for(i=1, n, A=1/x*serreverse(x/F); F=1+A*serreverse(x*F) + x*O(x^n)); polcoeff(A, n)}
for(n=0, 30, print1(a(n), ", "))
CROSSREFS
KEYWORD
sign
AUTHOR
Paul D. Hanna, Dec 22 2012
STATUS
approved