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%I #28 Apr 05 2024 11:07:04
%S 2,8,0,768,0,0,0,4954521600,0,0,0,20251509535014912000,0,0,0,
%T 88526812916367202104587059200000,0,0,0,
%U 3776127947893930552689423154306445475840000000,0,0,0,92624181047745713568610317051197596401168530978226831360000000,0,0,0,886156947284057553944669848348035536068124589065755283423684984832000000000000,0,0,0
%N Total number of distinct Hadamard matrices of order n.
%C a(n) is the total number of distinct Hadamard matrices of order n, ignoring all equivalences.
%H Brendan McKay, <a href="/A206712/b206712.txt">Table of n, a(n) for n = 1..35</a>
%H F. J. Aragon Artacho, J. M. Borwein, M. K. Tam, <a href="https://carmamaths.org/resources/jon/DR_MatrixCompletion.pdf">Douglas-Rachford Feasibility Methods for Matrix Completion Problems</a>, March 2014.
%H H. Kharaghani and B. Tayfeh-Rezaie, <a href="http://math.ipm.ac.ir/tayfeh-r/papersandpreprints/H32typetwo.pdf">Hadamard matrices of order 32</a>
%H <a href="/index/Ha#Hadamard">Index entries for sequences related to Hadamard matrices</a>
%F a(4n) = A206711(n) = A048615(n)/A048616(n) * (2^n * n!)^2.
%F For n>1, a(4n+1) = a(4n+2) = a(4n+3) = 0.
%Y Cf. A007299, A036297, A206711.
%K nonn,nice
%O 1,1
%A _Brendan McKay_, Feb 11 2012 (entered by _N. J. A. Sloane_)
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