OFFSET
0,3
COMMENTS
Series reversion of g.f. A(x) is -A(-x). The g.f. for A006196 (leftist trees with n leaves) also satisfies this condition: A(-A(-x)) = x. This sequence was inspired by communication with Michael Somos, while he was investigating this and similar functional equations and their resulting sequences.
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 0..270
FORMULA
G.f.: A(-A(-x)) = x.
PROG
(PARI) {a(n)=local(A); if(n<0, 0, A=x+x*O(x^n); for(i=1, n, B=subst(A, x, -x); C=subst(A, x, x+x*B); A=A+x+A*x-C); polcoeff(A, n, x))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Dec 05 2003
STATUS
approved