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 A159716 #12 May 19 2020 14:36:57
%S A159716 2,66,1168,16220,202416,2395540,27517568,310123764,3447919120,
%T A159716 37934904788,413863668480,4483624403284,48285543009872,
%U A159716 517346347249140,5518365322864384,58632646191319220,620816303380261392,6553061146974071956,68979591578665208960,724285713430953995412
%N A159716 Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly 2 local maxima.
%H A159716 Andrew Howroyd, <a href="/A159716/b159716.txt">Table of n, a(n) for n = 2..200</a>
%H A159716 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (29,-307,1467,-3240,2700).
%F A159716 a(n) = n*(169*10^(n-2) + 48*3^(n-2) - 84*n*3^(n-2))/49. - _Andrew Howroyd_, May 10 2020
%F A159716 From _Colin Barker_, May 19 2020: (Start)
%F A159716 G.f.: 2*x*(1 + 3*x)*(1 + x - 69*x^2 + 45*x^3) / ((1 - 3*x)^3*(1 - 10*x)^2).
%F A159716 a(n) = 29*a(n-1) - 307*a(n-2) + 1467*a(n-3) - 3240*a(n-4) + 2700*a(n-5) for n>6.
%F A159716 (End)
%o A159716 (PARI) a(n) = {n*(169*10^(n-2) + 48*3^(n-2) - 84*n*3^(n-2))/49} \\ _Andrew Howroyd_, May 10 2020
%o A159716 (PARI) Vec(2*x*(1 + 3*x)*(1 + x - 69*x^2 + 45*x^3) / ((1 - 3*x)^3*(1 - 10*x)^2) + O(x^20)) \\ _Colin Barker_, May 19 2020
%Y A159716 Column k=2 of A334772.
%K A159716 nonn,easy
%O A159716 2,1
%A A159716 _R. H. Hardin_, Apr 20 2009
%E A159716 Terms a(11) and beyond from _Andrew Howroyd_, May 09 2020