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 A206711 #32 Jul 08 2025 20:36:01 %S A206711 768,4954521600,20251509535014912000,88526812916367202104587059200000, %T A206711 3776127947893930552689423154306445475840000000, %U A206711 92624181047745713568610317051197596401168530978226831360000000,886156947284057553944669848348035536068124589065755283423684984832000000000000 %N A206711 Total number of distinct Hadamard matrices of order 4n. %C A206711 This is the total number of distinct Hadamard matrices of order 4n, ignoring all equivalences. %H A206711 Brendan McKay, <a href="/A206711/b206711.txt">Table of n, a(n) for n = 1..8</a> %H A206711 J. Dong, V. Elser, G. Gyawali, K. Y. Jee, J. Kent-Dobias, A. Mandaiya, M. Renz, Y. Su, <a href="https://arxiv.org/abs/1912.07558">Glass phenomenology in the hard matrix model</a>, arXiv:1912.07558 [cond-mat.stat-mech], 2019. %H A206711 H. Kharaghani and B. Tayfeh-Rezaie, <a href="https://math.ipm.ac.ir/~tayfeh-r/papersandpreprints/H32typetwo.pdf">Hadamard matrices of order 32</a>. %H A206711 <a href="/index/Ha#Hadamard">Index entries for sequences related to Hadamard matrices</a> %F A206711 a(n) = A048615(n)/A048616(n) * (2^n * n!)^2. %F A206711 a(n) = A206712(4n). %Y A206711 Cf. A007299, A036297, A206712. %K A206711 nonn,nice %O A206711 1,1 %A A206711 _Brendan McKay_, Feb 11 2012 (entered by _N. J. A. Sloane_)