A120959 G.f.: A(x) = 1+x*(1+x*(1+x*(...(1+x*(...)^(2^n) )...)^8)^4)^2.

1, 1, 2, 9, 84, 1540, 54522, 3734454, 498851832, 131025111932, 68094916593416, 70324929555472825, 144712913119662777792, 594305955799647611394896, 4875569433937264188593935824, 79943787791004406866072303453528

Offset: 0

Author

Paul D. Hanna, Jul 28 2006

Keywords

• nonn

Comments

Limit a(n)/2^[n*(n-1)/2] = 1.97254925752982255...

Examples

			G.f.: A(x) = 1 + x*B(x)^2; B(x) = 1 + x*C(x)^4; C(x) = 1 + x*D(x)^8;
D(x) = 1 + x*E(x)^16; E(x) = 1 + x*F(x)^32; ...
where the respective sequences begin:
B=[1,1,4,38,724,26385,1837224,247455640,65256486712,...];
C=[1,1,8,156,6008,436870,60346328,16118073852,8445009616488,...];
D=[1,1,16,632,48944,7110684,1956587408,1040720206536,...];
E=[1,1,32,2544,395104,114749560,63023951008,66902165283280,...];
F=[1,1,64,10208,3175104,1843872240,2023417888576,...].
		

Crossrefs

Cf. A234296, A095793.

Programs

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)}