A138213 G.f.: A(x) = 1 + x*(1 + x*(1 + x*(...(1 + x*(...)^(3n))...)^9)^6)^3.

1, 1, 3, 21, 244, 4002, 84909, 2209947, 68121822, 2425846806, 97969327890, 4423628854404, 220806455598561, 12072207455321168, 717431790926502954, 46045783798588216767, 3174068594948910976851, 233875508656473241657578

Offset

0,3

Links

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

Example

G.f.: A(x)=1+x*B(x)^3, B(x)=1+x*C(x)^6, C(x)=1+x*D(x)^9, D(x)=1+x*E(x)^12,...
where A(x),B(x),C(x),... are the g.f. of the sequences given below.
A=[1,1,3,21,244,4002,84909,2209947,68121822,2425846806,...];
B=[1,1,6,69,1154,25062,665862,20869399,752900220,30714860088,...];
C=[1,1,9,144,3162,86346,2789703,103536696,4329341244,...];
D=[1,1,12,246,6700,221145,8453892,364604520,17444393868,...];
E=[1,1,15,375,12200,472875,20921433,1031067730,55735025670,...];
F=[1,1,18,531,20094,895077,45035802,2500543500,150992211456,...]; ...

Prog

(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(j=0, n-1, A=1+x*A^(3*(n-j))); polcoeff(A, n)}

Crossrefs

Cf. A095793, A138211, A138212, A138214, A138215, A138216.

Sequence in context: A058562 A145083 A234303 * A193333 A290129 A365602

Adjacent sequences: A138210 A138211 A138212 * A138214 A138215 A138216

Keyword

nonn

Author

Paul D. Hanna, Mar 06 2008

Status

approved