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 A184287 #17 Nov 01 2017 12:23:31
%S A184287 165,49075,20346485,9536816875,4768372070757,2483526896194175,
%T A184287 1330460821097243445,727595761432647851875,404219867454740749892485,
%U A184287 227373675443239212037148635,129189588320018269798974609525,74014868308343773086872161914375
%N A184287 Number of distinct n X 4 toroidal 0..4 arrays.
%H A184287 Andrew Howroyd, <a href="/A184287/b184287.txt">Table of n, a(n) for n = 1..100</a>
%t A184287 T[n_, k_] := (1/(n*k))*Sum[Sum[EulerPhi[c]*EulerPhi[d]*5^(n*k/LCM[c, d]), {d, Divisors[k]}], {c, Divisors[n]}]; a[n_] := T[n, 4]; Array[a, 12] (* _Jean-François Alcover_, Nov 01 2017, after _Andrew Howroyd_ *)
%o A184287 (PARI) a(n) = my(k=4); (1/(n*k)) * sumdiv(n, c, sumdiv(k, d, eulerphi(c) * eulerphi(d) * 5^(n*k/lcm(c, d)))); \\ _Michel Marcus_, Nov 01 2017
%Y A184287 Column 4 of A184288.
%K A184287 nonn
%O A184287 1,1
%A A184287 _R. H. Hardin_, Jan 10 2011
%E A184287 Terms a(6) and beyond from _Andrew Howroyd_, Sep 27 2017