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 A090769 #13 Jul 07 2025 03:31:32
%S A090769 7,115248,4648735526400,450407556363158605209600,
%T A090769 104778523164913973815626804401602560000,
%U A090769 58523610551335889301209607995669952696063684472995840000,78484177614161178233131678359243733693084949841898468389173730723495936000000,252711655239728880943018718373465881336679551349902568778399448766444479481704737212965012373504000000
%N A090769 a(n) = 7^(n^2+2n+1)*Product_{j=1..n} (49^j-1).
%C A090769 The order of the p-Clifford group for an odd prime p is a*p^(n^2+2n+1)*Product_{j=1..n} (p^(2*j)-1), where a = gcd(p+1,4).
%H A090769 G. Nebe, E. M. Rains and N. J. A. Sloane, <a href="http://neilsloane.com/doc/cliff2.html">Self-Dual Codes and Invariant Theory</a>, Springer, Berlin, 2006.
%F A090769 From _Amiram Eldar_, Jul 07 2025: (Start)
%F A090769 a(n) = A090768(n) / 4.
%F A090769 a(n) ~ c * 7^(2*n^2+3*n+1), where c = Product_{k>=1} (1 - 1/7^(2*k)) = 0.979175347148... . (End)
%t A090769 Table[7^(n^2 + 2 n + 1)*Product[49^j - 1, {j, n}], {n, 0, 7}] (* _Wesley Ivan Hurt_, Oct 15 2023 *)
%Y A090769 Cf. A001309, A003956.
%Y A090769 Cf. A092299 and A092301 (p=3), A092300 and A089989 (p=5), A090768 and A090769 (p=7), A090770 (p=2, although this is the wrong formula in that case).
%K A090769 nonn
%O A090769 0,1
%A A090769 _N. J. A. Sloane_, Feb 10 2004