OFFSET
0,3
EXAMPLE
G.f.: A(x)=1+x*B(x)^6, B(x)=1+x*C(x)^12, C(x)=1+x*D(x)^18, D(x)=1+x*E(x)^24,...
where A(x),B(x),C(x),... are the g.f. of the sequences given below.
A=[1,1,6,87,2072,69051,2960496,155190175,9614870340,...];
B=[1,1,12,282,9616,424035,22794444,1441538178,104721633324,...];
C=[1,1,18,585,26088,1443708,94316940,7064386296,595172880432,...];
D=[1,1,24,996,54944,3668826,283322664,24650121400,2376215009736,...];
E=[1,1,30,1515,99640,7802145,696663576,69221991825,7536986249580,...];
F=[1,1,36,2142,163632,14708421,1492326612,166960071642,...]; ...
PROG
(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(j=0, n-1, A=1+x*A^(6*(n-j))); polcoeff(A, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Mar 06 2008
STATUS
approved