OFFSET
0,3
COMMENTS
Limit a(n)/4^[n(n-1)/2] = 1.2167020033386380312738338894882216...
EXAMPLE
G.f.: A(x) = 1 + x + 4*x^2 + 70*x^3 + 4772*x^4 + 1256737*x^5 +...
Related functions are defined by:
A(x) = 1 + x*B(x)^4;
B(x) = 1 + x*C(x)^16;
C(x) = 1 + x*D(x)^64;
D(x) = 1 + x*E(x)^256;
E(x) = 1 + x*F(x)^1024; ...
where the coefficients in the above functions begin:
B=[1,1,16,1144,310320,324057372,1334856912400,21904872061736520,...];
C=[1,1,64,18400,19940032,83109401072,1367783819781952,...];
D=[1,1,256,294784,1277438720,21285675278272,1400838812478999808,...];
E=[1,1,1024,4718080,81776520192,5449752029298432,1434517374576707974144,...];
F=[1,1,4096,75495424,5234024427520,1395176151497833472,...].
PROG
(PARI) {a(n)=local(A=1+x+x*O(x^n)); for(j=0, n-1, A=1+x*A^(4^(n-j))); polcoeff(A, n)}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jan 17 2011
STATUS
approved