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

0,2

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

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 *)

Crossrefs

Cf. A034899, A144074.

Sequence in context: A357035 A370713 A026546 * A151020 A151021 A151022

Adjacent sequences: A256102 A256103 A256104 * A256106 A256107 A256108

Keyword

nonn

Author

Vaclav Kotesovec, Mar 14 2015

Status

approved