A184266 Number of distinct n X 4 toroidal binary arrays.

6, 40, 352, 4156, 52488, 699600, 9587580, 134223976, 1908881900, 27487869472, 399822505524, 5864063067176, 86607686432616, 1286742765058960, 19215358428046176, 288230376353050696, 4340410370537249376, 65588423376053309360, 994182417449857925988

Offset

1,1

Links

Vaclav Kotesovec, Table of n, a(n) for n = 1..820

S. N. Ethier, Counting toroidal binary arrays, arXiv preprint arXiv:1301.2352, 2013 and J. Int. Seq. 16 (2013) #13.4.7.

Formula

a(n) ~ 2^(4*n-2) / n. - Vaclav Kotesovec, Sep 04 2014

Maple

with(numtheory):
a:= n-> add(add(phi(c)*phi(d) *2^(4*n/ilcm(c, d)),
        d=divisors(n)), c=[1, 2, 4])/(4*n):
seq(a(n), n=1..30);  # Alois P. Heinz, Aug 25 2012

Crossrefs

Column 4 of A184271.

Sequence in context: A341587 A006387 A014481 * A000683 A352357 A143342

Adjacent sequences: A184263 A184264 A184265 * A184267 A184268 A184269

Keyword

nonn

Author

R. H. Hardin, Jan 10 2011

Extensions

More terms from Alois P. Heinz, Aug 25 2012

Status

approved