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 A003930 #15 Jul 11 2025 15:37:01
%S A003930 360,1721606400,54025731402499584000,
%T A003930 11123418742298669930322238341120000,
%U A003930 15026089310120671289900284876259193821694984192000000,133175299735499915203175849633922453238030221758644323033296865853440000000
%N A003930 Order of simple Chevalley group B_n (9).
%H A003930 <a href="/index/Gre#groups">Index entries for sequences related to groups</a>.
%F A003930 a(n) = b(9,n) where b(q,n) is defined in A003927. - _Sean A. Irvine_, Sep 22 2015
%F A003930 a(n) ~ c * 9^(2*n^2+n)/2, where c = Product_{k>=1} (1 - 1/9^(2*k)) = 0.987501905484... . - _Amiram Eldar_, Jul 11 2025
%t A003930 b[q_, n_] := q^(n^2) * Product[q^(2*k) - 1, {k, 1, n}] / GCD[2, q-1]; Table[b[9, n], {n, 1, 6}] (* _Amiram Eldar_, Jul 11 2025 *)
%Y A003930 Cf. A003927, A003928, A003929.
%K A003930 nonn
%O A003930 1,1
%A A003930 _N. J. A. Sloane_
%E A003930 a(6) from _Sean A. Irvine_, Sep 22 2015