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 A003931 #25 Jun 24 2025 05:49:08
%S A003931 720,51840,979200,9360000,276595200,1056706560,3443212800,25721308800,
%T A003931 137037962880,1095199948800,2008994088960,6114035779200,
%U A003931 41348052472320,95214600000000,205608315669120,420206392771200,818774509363200,1124799322521600,4805069329111680,13414669637644800
%N A003931 Order of universal Chevalley group B_2(q), q = prime power.
%D A003931 J. H. Conway, R. T. Curtis, S. P. Norton, R. A. Parker and R. A. Wilson, ATLAS of Finite Groups. Oxford Univ. Press, 1985 [for best online version see https://oeis.org/wiki/Welcome#Links_to_Other_Sites], p. xvi.
%D A003931 H. S. M. Coxeter and W. O. J. Moser, Generators and Relations for Discrete Groups, 4th ed., Springer-Verlag, NY, reprinted 1984, p. 131.
%H A003931 Robin Visser, <a href="/A003931/b003931.txt">Table of n, a(n) for n = 1..10000</a>
%H A003931 <a href="/index/Gre#groups">Index entries for sequences related to groups</a>.
%F A003931 a(n) = B(A000961(n + 1), 2) where B(q,n) is defined in A003920. - _Sean A. Irvine_, Sep 22 2015
%t A003931 B[q_, n_] := q^(n^2) * Product[q^(2*k) - 1, {k, 1, n}]; Table[B[q, 2], {q, Select[Range[50], PrimePowerQ]}] (* _Amiram Eldar_, Jun 24 2025 *)
%o A003931 (Magma) [#SymplecticGroup(4,q) : q in [2..50] | IsPrimePower(q)]; // _Robin Visser_, Aug 06 2023
%Y A003931 Cf. A000961, A003920, A003932, A003933, A003934, A003935, A003936, A003937.
%K A003931 nonn,easy
%O A003931 1,1
%A A003931 _N. J. A. Sloane_
%E A003931 More terms from _Robin Visser_, Aug 06 2023