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

Author

R. H. Hardin, Jan 10 2011

Keywords

• nonn

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.

Crossrefs

Column 4 of A184271.

Programs

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

Formula

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

Extensions

More terms from Alois P. Heinz, Aug 25 2012