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A120959 G.f.: A(x) = 1+x*(1+x*(1+x*(...(1+x*(...)^(2^n) )...)^8)^4)^2. 5
1, 1, 2, 9, 84, 1540, 54522, 3734454, 498851832, 131025111932, 68094916593416, 70324929555472825, 144712913119662777792, 594305955799647611394896, 4875569433937264188593935824, 79943787791004406866072303453528 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

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

LINKS

Table of n, a(n) for n=0..15.

EXAMPLE

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,...].

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. A234296, A095793.

Sequence in context: A086929 A193466 A262011 * A125797 A068595 A330475

Adjacent sequences:  A120956 A120957 A120958 * A120960 A120961 A120962

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jul 28 2006

STATUS

approved

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Last modified June 15 11:22 EDT 2021. Contains 345048 sequences. (Running on oeis4.)