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 A152496 #8 May 12 2020 11:45:02
%S A152496 0,0,0,113,16565,1216902,65819156,3026987243,126794945523,
%T A152496 5020186173560,191940972943658,7179017518306893,264789361664356313,
%U A152496 9680016979445645738,351879352694331441600,12745281650338440074831,460591166578400672643359,16621008007245773574764028
%N A152496 1/3 of the number of permutations of 2 indistinguishable copies of 1..n with exactly 4 local maxima.
%H A152496 Andrew Howroyd, <a href="/A152496/b152496.txt">Table of n, a(n) for n = 1..200</a>
%F A152496 a(n) = A334774(n,4)/3. - _Andrew Howroyd_, May 12 2020
%o A152496 (PARI) \\ PeaksBySig defined in A334774.
%o A152496 a(n)={PeaksBySig(vector(n,i,2), [3])[1]/3} \\ _Andrew Howroyd_, May 12 2020
%Y A152496 Cf. A334774.
%K A152496 nonn
%O A152496 1,4
%A A152496 _R. H. Hardin_, Dec 06 2008
%E A152496 Terms a(11) and beyond from _Andrew Howroyd_, May 11 2020