A128328 Row 3 of table A128325.

1, 1, 5, 30, 200, 1435, 10900, 86799, 720074, 6196295, 55135043, 506125404, 4784680169, 46516469860, 464550190798, 4761343733469, 50044839978614, 539051253692777, 5946806890025709, 67156408547628636, 775935817487472046

Offset: 0

Author

Paul D. Hanna, Mar 11 2007

Keywords

• nonn

Crossrefs

Cf. A030266; A128325 (table), A128326 (row 1), A128327 (row 2), A128329 (main diagonal).

Programs

PARI

{a(n)=local(A=1+x,B);for(i=0,n,A=1+x*A*subst(A,x,x*A+x*O(x^n))); B=A;for(i=1,3,B=subst(B,x,x*A+x*O(x^n)));polcoeff(B,n)}

Formula

G.f.: A(x) = 1 + G(G(G(G(G(x))))) = B(G(x)), where B(x) is the g.f. of A128327 and G(x) = x + x*G(G(x)) is the g.f. of A030266.