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A048616
Denominator of mass (Sum 1/|Aut(H)|) of Hadamard matrices of order 4n.
5
192, 21504, 190080, 573440, 218880, 40480, 2106, 53329920
OFFSET
1,1
LINKS
V. Alvarez, J. A. Armario, M. D. Frau and F. Gudiel, The maximal determinant of cocyclic (-1, 1)-matrices over D_{2t}, Linear Algebra and its Applications, 2011.
EXAMPLE
1/192, 1/21504, 1/190080, 27/573440, 127/218880, 34603/40480, 278617/2106, 264156210586399/53329920, ...
CROSSREFS
KEYWORD
frac,nonn,hard,nice
AUTHOR
N. J. A. Sloane, E. M. Rains
EXTENSIONS
a(8) from Brendan McKay, Feb 11 2012
STATUS
approved