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 A003834 #19 Jul 08 2025 07:50:23
%S A003834 6,112896,4635182361600,450219964711195607040000,
%T A003834 104772288945650279285144527564308480000,
%U A003834 58523113108854003897259712887271278079596939632967680000
%N A003834 Order of universal Chevalley group D_n (7).
%D A003834 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 A003834 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 A003834 <a href="/index/Gre#groups">Index entries for sequences related to groups</a>.
%F A003834 a(n) = D(7,n) where D(q,n) is defined in A003830. - _Sean A. Irvine_, Sep 17 2015
%F A003834 a(n) ~ c * 7^(n*(2*n-1)), where c = Product_{k>=1} (1 - 1/7^(2*k)) = 0.979175347148... . - _Amiram Eldar_, Jul 08 2025
%t A003834 d[q_, n_] := q^(n*(n-1)) * (q^n-1) * Product[q^(2*k) - 1, {k, 1, n-1}]; Table[d[7, n], {n, 1, 8}] (* _Amiram Eldar_, Jun 24 2025 *)
%Y A003834 Cf. A003830, A003831, A003832, A003835, A003836.
%K A003834 nonn,easy
%O A003834 1,1
%A A003834 _N. J. A. Sloane_