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A128329 Main diagonal of table A128325. 5
1, 1, 4, 30, 321, 4389, 72512, 1399755, 30865353, 764755508, 21024535960, 634924059276, 20890221475598, 743727414390456, 28484480606420928, 1167761832049224515, 51022550712426870397, 2366859765773183488674 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..17.

FORMULA

a(n) = [x^n] {1 + H(x)}, where H(x) is the (n+2)-th self-composition of G(x) 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, n, B=subst(B, x, x*A+x*O(x^n))); polcoeff(B, n)}

CROSSREFS

Cf. A030266; A128325 (table), A128326 (row 1), A128327 (row 2), A128328 (row 3).

Sequence in context: A298244 A293191 A180623 * A211828 A277759 A006149

Adjacent sequences: A128326 A128327 A128328 * A128330 A128331 A128332

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 11 2007

STATUS

approved

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Last modified January 26 22:13 EST 2023. Contains 359836 sequences. (Running on oeis4.)