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 A334779 #10 May 18 2020 10:48:36
%S A334779 1,1,2,6,88,1480,40272,1476944,71865728,4454840448,343059301120,
%T A334779 32120367997696,3593423957597184,473387964389590016,
%U A334779 72533147097036867584,12789470502905585018880,2571336187676016073080832,584713932920281483718459392,149314675071137196105777217536
%N A334779 Number of permutations of 2 indistinguishable copies of 1..n arranged in a circle with exactly n local maxima.
%H A334779 Andrew Howroyd, <a href="/A334779/b334779.txt">Table of n, a(n) for n = 0..100</a>
%o A334779 (PARI) \\ CircPeaksBySig defined in A334778.
%o A334779 a(n) = {if(n==0, 1, CircPeaksBySig(vector(n, i, 2), [n])[1])} \\ _Andrew Howroyd_, May 13 2020
%Y A334779 Main diagonal of A334778.
%K A334779 nonn
%O A334779 0,3
%A A334779 _Andrew Howroyd_, May 13 2020