

A048615


Numerator of mass (Sum 1/Aut(H)) of Hadamard matrices of order 4n.


5




OFFSET

1,4


COMMENTS

This list starts with the Hadamard matrix of order 4. The masses of the Hadamard matrices of orders 1 and 2 are 1/2 and 1/8 respectively.


LINKS

Table of n, a(n) for n=1..8.
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.
Index entries for sequences related to Hadamard matrices


EXAMPLE

1/192, 1/21504, 1/190080, 27/573440, 127/218880, 34603/40480, 278617/2106, 264156210586399/53329920, ...


CROSSREFS

Cf. A048616, A007299, A036297.
Sequence in context: A044740 A026917 A267935 * A124955 A126414 A183427
Adjacent sequences: A048612 A048613 A048614 * A048616 A048617 A048618


KEYWORD

frac,nonn,hard,nice


AUTHOR

N. J. A. Sloane, E. M. Rains


EXTENSIONS

a(8) from Brendan McKay, Feb 11 2012


STATUS

approved



