A371547 Expansion of e.g.f. Product_{k>=1} 1 / (1 - 2*x^k/k).
1, 2, 10, 64, 548, 5608, 68936, 973600, 15700352, 283559424, 5685644928, 125227712256, 3007981305600, 78237291643392, 2191215982262784, 65744691667064832, 2103999919044163584, 71538799576401408000, 2575460412946013810688, 97868678834373255069696, 3914776163575281528889344
Offset: 0
Keywords
Programs
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Mathematica
nmax = 20; CoefficientList[Series[Product[1/(1 - 2 x^k/k), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
Formula
a(n) ~ c * 2^n * n!, where c = Product_{k>=2} 1/(1 - 2^(1-k)/k) = 1.5345676172355916355224667976662106649465582052467986508967405417359... - Vaclav Kotesovec, Mar 28 2024