This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A184266 #20 Jan 20 2018 16:13:41 %S A184266 6,40,352,4156,52488,699600,9587580,134223976,1908881900,27487869472, %T A184266 399822505524,5864063067176,86607686432616,1286742765058960, %U A184266 19215358428046176,288230376353050696,4340410370537249376,65588423376053309360,994182417449857925988 %N A184266 Number of distinct n X 4 toroidal binary arrays. %H A184266 Vaclav Kotesovec, <a href="/A184266/b184266.txt">Table of n, a(n) for n = 1..820</a> %H A184266 S. N. Ethier, <a href="http://arxiv.org/abs/1301.2352">Counting toroidal binary arrays</a>, arXiv preprint arXiv:1301.2352, 2013 and <a href="https://cs.uwaterloo.ca/journals/JIS/VOL16/Ethier/ethier2.html">J. Int. Seq. 16 (2013) #13.4.7</a>. %F A184266 a(n) ~ 2^(4*n-2) / n. - _Vaclav Kotesovec_, Sep 04 2014 %p A184266 with(numtheory): %p A184266 a:= n-> add(add(phi(c)*phi(d) *2^(4*n/ilcm(c, d)), %p A184266 d=divisors(n)), c=[1,2,4])/(4*n): %p A184266 seq(a(n), n=1..30); # _Alois P. Heinz_, Aug 25 2012 %Y A184266 Column 4 of A184271. %K A184266 nonn %O A184266 1,1 %A A184266 _R. H. Hardin_, Jan 10 2011 %E A184266 More terms from _Alois P. Heinz_, Aug 25 2012