OFFSET
1,1
LINKS
Vaclav Kotesovec, Table of n, a(n) for n = 1..470
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) ~ 128^n / (7*n). - Vaclav Kotesovec, Sep 04 2014
MAPLE
with(numtheory):
a:= n-> add(add(phi(c)*phi(d) *2^(7*n/ilcm(c, d)),
d=divisors(n)), c=[1, 7])/(7*n):
seq(a(n), n=1..20); # Alois P. Heinz, Aug 25 2012
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 10 2011
EXTENSIONS
More terms from Alois P. Heinz, Aug 25 2012
STATUS
approved