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

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

Offset: 1

Author

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

Keywords

• frac
• nonn
• hard
• nice

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.

Examples

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

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.
• Index entries for sequences related to Hadamard matrices

Crossrefs

Cf. A048616, A007299, A036297.

Extensions

a(8) from Brendan McKay, Feb 11 2012