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 A184290 #17 Nov 01 2017 12:23:47
%S A184290 76,7826,1119936,181402676,31345666736,5642220395616,1044616697187576,
%T A184290 197432555854243976,37907050706575921296,7369130657373455467336,
%U A184290 1447029292717527455513576,286511799958073253432316896,57126045037793735333314420176
%N A184290 Number of distinct n X 3 toroidal 0..5 arrays.
%H A184290 Andrew Howroyd, <a href="/A184290/b184290.txt">Table of n, a(n) for n = 1..100</a>
%t A184290 T[n_, k_] := (1/(n*k))*Sum[Sum[EulerPhi[c]*EulerPhi[d]*6^(n*(k/LCM[c, d])), {d, Divisors[k]}], {c, Divisors[n]}]; a[n_] := T[n, 3]; Array[a, 13] (* _Jean-François Alcover_, Nov 01 2017, after _Andrew Howroyd_ *)
%o A184290 (PARI) a(n) = my(k=3); (1/(n*k)) * sumdiv(n, c, sumdiv(k, d, eulerphi(c) * eulerphi(d) * 6^(n*k/lcm(c, d)))); \\ _Michel Marcus_, Nov 01 2017
%Y A184290 Column 3 of A184291.
%K A184290 nonn
%O A184290 1,1
%A A184290 _R. H. Hardin_, Jan 10 2011
%E A184290 Terms a(7) and beyond from _Andrew Howroyd_, Sep 27 2017