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 A333508 #6 Mar 25 2020 13:45:23
%S A333508 1,2,6,30,212,1924,21280,277788,4180544,71259048,1356909620,
%T A333508 28547946524,657640647850,16463431995932,445040788849348,
%U A333508 12919664598624526,400880326987609778,13239976828676088316,463742797180250495450,17169969365226035615744
%N A333508 Central coefficients of polynomials related to Weyl groups and defined in A162206.
%t A333508 a[n_] := SeriesCoefficient[(1-x^n) Product[1-x^(2k), {k, 1, n-1}]/(1-x)^n, {x, 0, n(n-1)/2}];
%t A333508 Array[a, 20]
%Y A333508 Cf. A162206 - A162212, A162248, A162288, A162297, A162300, A162301, A162321, A162327, A162328, A162346, A162347, A162359.
%K A333508 nonn
%O A333508 1,2
%A A333508 _Jean-François Alcover_, Mar 25 2020