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Number of partitions of 2^n into parts that are at most n.
11

%I #20 Nov 03 2018 18:46:53

%S 0,1,3,10,64,831,26207,2239706,567852809,454241403975,

%T 1192075219982204,10510218491798860052,315981966712495811700951,

%U 32726459268483342710907384794,11771239570056489326716955796095261,14808470136486015545654676685321653888199

%N Number of partitions of 2^n into parts that are at most n.

%H Alois P. Heinz, <a href="/A237998/b237998.txt">Table of n, a(n) for n = 0..62</a>

%H A. V. Sills and D. Zeilberger, <a href="https://arxiv.org/abs/1108.4391">Formulae for the number of partitions of n into at most m parts (using the quasi-polynomial ansatz)</a> (arXiv:1108.4391 [math.CO])

%F a(n) = [x^(2^n)] Product_{j=1..n} 1/(1-x^j).

%F a(n) ~ 2^(n*(n-1)) / (n!*(n-1)!). - _Vaclav Kotesovec_, Jun 05 2015

%e a(1) = 1: 11.

%e a(2) = 3: 22, 211, 1111.

%e a(3) = 10: 332, 2222, 3221, 3311, 22211, 32111, 221111, 311111, 2111111, 11111111.

%t a[n_] := SeriesCoefficient[Product[1/(1 - x^j), {j, 1, n}], {x, 0, 2^n}];

%t Table[a[n], {n, 0, 12}] (* _Jean-François Alcover_, Nov 03 2018 *)

%Y Column k=2 of A238010.

%Y Cf. A236810, A237512, A237999, A238000, A238001, A258672.

%K nonn

%O 0,3

%A _Alois P. Heinz_, Feb 16 2014