A048615 Numerator of mass (Sum 1/|Aut(H)|) of Hadamard matrices of order 4n.

1, 1, 1, 27, 127, 34603, 278617, 264156210586399

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