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A138212 G.f.: A(x) = 1 + x*(1 + x*(1 + x*(...(1 + x*(...)^(2n))...)^6)^4)^2. 8
1, 1, 2, 9, 68, 732, 10250, 176654, 3613044, 85476720, 2295275372, 68949496421, 2290588299708, 83374406924240, 3299390271801838, 141034101443780374, 6475752407825487220, 317866884692663325892, 16609896989101220207880 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..18.

EXAMPLE

G.f.: A(x)=1+x*B(x)^2, B(x)=1+x*C(x)^4, C(x)=1+x*D(x)^6, D(x)=1+x*E(x)^8, ...

where A(x),B(x),C(x),... are the g.f. of the sequences given below.

A=[1,1,2,9,68,732,10250,176654,3613044,85476720,...];

B=[1,1,4,30,328,4677,81888,1696086,40520620,1096342026,...];

C=[1,1,6,63,908,16311,347466,8519957,235763712,7259384208,...];

D=[1,1,8,108,1936,42110,1062416,30283824,958845640,...];

E=[1,1,10,165,3540,90550,2646522,86251140,3086189660,...];

F=[1,1,12,234,5848,172107,5725392,210342902,8410505748,...]; ...

PROG

(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(j=0, n-1, A=1+x*A^(2*(n-j))); polcoeff(A, n)}

CROSSREFS

Cf. A095793, A138211, A138213, A138214, A138215, A138216.

Sequence in context: A134200 A217066 A038037 * A134261 A120980 A020563

Adjacent sequences:  A138209 A138210 A138211 * A138213 A138214 A138215

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 06 2008

STATUS

approved

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Last modified April 18 10:44 EDT 2019. Contains 322209 sequences. (Running on oeis4.)