A256105 a(n) = [x^n] 2^(2*n) / Product_{k>=1} (1-x^k)^(2^(-k)).

1, 2, 10, 36, 166, 556, 2724, 9000, 41542, 153164, 657644, 2325816, 11020508, 38006264, 164662664, 634362320, 2695771462, 9775537676, 43527018396, 156855914904, 687387270260, 2605392165928, 10799896586616, 40214700074800, 178809945153820, 657023566793400

Offset: 0

Author

Vaclav Kotesovec, Mar 14 2015

Keywords

• nonn

Comments

Limit n->infinity a(n)^(1/n) = 4.

Links

• Vaclav Kotesovec, Table of n, a(n) for n = 0..500
• Vaclav Kotesovec, Graph a(n)/4^n

Crossrefs

Cf. A034899, A144074.

Programs

Mathematica

Table[2^(2*n) * SeriesCoefficient[Product[1/(1-x^k)^(2^(-k)),{k,1,n}],{x,0,n}], {n,0,30}]
Table[4^n * (CoefficientList[Series[Exp[Sum[x^k/(2*k*(1-x^k/2)),{k,1,n}]],{x,0,n}],x])[[n+1]],{n,0,30}] (* faster *)