0,4

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

G.f.: A(x) = 1 + x/B(x); B(x) = 1 + x/C(x)^2; C(x) = 1 + x/D(x)^4;

D(x) = 1 + x/E(x)^8; E(x) = 1 + x/F(x)^16; ...

where the respective sequences begin:

B=[1,1,-2,11,-112,2025,-67324,4305909,-545113744,...];

C=[1,1,-4,42,-836,30259,-2041616,265712044,-68214603840,...];

D=[1,1,-8,164,-6456,467850,-63614840,16702037652,...];

E=[1,1,-16,648,-50736,7358500,-2008876560,1059405119352,...];

F=[1,1,-32,2576,-402272,116732040,-63860549280,...].

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

Cf. A120959 (variant).

Sequence in context: A062873 A109398 A006058 this_sequence A125281 A086371 A135753

Adjacent sequences: A121585 A121586 A121587 this_sequence A121589 A121590 A121591

sign

Paul D. Hanna (pauldhanna(AT)juno.com), Aug 09 2006