OFFSET
0,2
LINKS
Seiichi Manyama, Table of n, a(n) for n = 0..3309
FORMULA
a(n) = [x^(2*n)] Product_{k>=0} 1/(1 - 2^k*x^(2^k)). - Ilya Gutkovskiy, Sep 10 2018
a(n) ~ c * n * 2^n, where c = 2.1343755406794500897789546611306737041750472866941557748356... - Vaclav Kotesovec, Jun 18 2019
EXAMPLE
n | partitions of 2*n into powers of 2 | a(n)
--------------------------------------------------------------------------
1 | 2 , 1+1 | 2+1 = 3.
2 | 4 , 2+2 , 2+1+1, 1+1+1+1 | 4+4+2+1 = 11.
3 | 4+2, 4+1+1, 2+2+2, 2+2+1+1, 2+1+1+1+1, 1+1+1+1+1+1 | 8+4+8+4+2+1 = 27.
MAPLE
b:= proc(n, i, p) option remember; `if`(n=0, p,
`if`(i<1, 0, add(b(n-j*i, i/2, p*i^j), j=0..n/i)))
end:
a:= n-> (t-> b(t, 2^ilog2(t), 1))(2*n):
seq(a(n), n=0..33); # Alois P. Heinz, Oct 27 2017
MATHEMATICA
b[n_, i_, p_] := b[n, i, p] = If[n == 0, p, If[i < 1, 0, Sum[b[n - j i, i/2, p i^j], {j, 0, n/i}]]];
a[n_] := b[2n, 2^Floor@Log[2, 2n], 1];
a /@ Range[0, 33] (* Jean-François Alcover, Nov 23 2020, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Oct 27 2017
STATUS
approved