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

0,3

Links

Table of n, a(n) for n=0..20.

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.

Prog

(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)}

Crossrefs

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

Sequence in context: A090139 A107265 A196678 * A245376 A118346 A234422

Adjacent sequences: A128325 A128326 A128327 * A128329 A128330 A128331

Keyword

nonn

Author

Paul D. Hanna, Mar 11 2007

Status

approved