OFFSET
0,3
FORMULA
G.f. satisfies: x - G(x) = G(x)^2*A(x)^4 where G(x*A(x)) = x.
EXAMPLE
G.f.: A(x) = 1 + x + 4*x^2 + 26*x^3 + 216*x^4 + 2091*x^5 + 22532*x^6 +...
A(x*A(x)) = 1 + x + 5*x^2 + 38*x^3 + 356*x^4 + 3801*x^5 + 44508*x^6 +...
A(x*A(x))^4 = 1 + 4*x + 26*x^2 + 216*x^3 + 2091*x^4 + 22532*x^5 +...
PROG
(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(i=0, n, A=1+x*subst(A^4, x, x*A)); polcoeff(A, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Aug 14 2008
STATUS
approved