OFFSET
0,3
EXAMPLE
G.f.: A(x) = 1 + x + 2*x^2 + 8*x^3 + 26*x^4 + 56*x^5 + 194*x^6 + 832*x^7 +...
Related expansions begin:
A(x)^2 = 1 + 2*x + 5*x^2 + 20*x^3 + 72*x^4 + 196*x^5 + 668*x^6 + 2692*x^7 +...
A(I*x)*A(-I*x) = 1 - 3*x^2 + 40*x^4 - 316*x^6 + 4624*x^8 - 50676*x^10 + 811192*x^12 -+...
PROG
(PARI) {a(n)=local(A=1+x); for(i=1, n, A=1+x*A^2/(subst(A, x, I*x+x*O(x^n))*subst(A, x, -I*x+x*O(x^n)))); polcoeff(A, n)}
for(n=0, 30, print1(a(n), ", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jun 13 2012
STATUS
approved