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 A282819 #12 Feb 23 2017 04:27:43
%S A282819 0,0,2,22,152,680,2270,6202,14672,31152,60810,110990,191752,316472,
%T A282819 502502,771890,1152160,1677152,2387922,3333702,4572920,6174280,
%U A282819 8217902,10796522,14016752,18000400,22885850,28829502,36007272,44616152,54875830,67030370,81349952
%N A282819 Number of inequivalent ways to color the edges of a tetrahedron using at most n colors so that no two opposite edges have the same color.
%H A282819 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-7,1).
%F A282819 a(n) = n*(n-1)*(n^4-2*n^3+n^2+8)/12.
%F A282819 G.f.: -2*x^2*(1+4*x+20*x^2+4*x^3+x^4) / (x-1)^7 . - _R. J. Mathar_, Feb 23 2017
%F A282819 a(n) = 2*A282816(n). - _R. J. Mathar_, Feb 23 2017
%e A282819 For n = 2 we get a(2) = 2 distinct ways to color the edges of a tetrahedron in two colors so that no two opposite edges have the same color.
%t A282819 Table[(n - 1) n (n^4 - 2 n^3 + n^2 + 8)/12, {n, 0, 33}]
%o A282819 (PARI) a(n) = n*(n-1)*(n^4-2*n^3+n^2+8)/12 \\ _Charles R Greathouse IV_, Feb 22 2017
%Y A282819 Cf. A282816, A282818, A282820. A046023 (tetrahedral edge colorings without restriction).
%K A282819 nonn,easy
%O A282819 0,3
%A A282819 _David Nacin_, Feb 22 2017