A001111 Number of inequivalent Hadamard designs of order 4n.

1, 1, 1, 5, 6, 1106, 208310, 10374196953

Offset

1,4

Comments

In other words, number of 2-(4*n-1,2*n-1,n-1) symmetric designs.

Links

Table of n, a(n) for n=1..8.

R. K. Guy, Letters to N. J. A. Sloane, June-August 1968.

Edward Spence, Hadamard matrices.

Edward Spence, Classification of Hadamard matrices of order 24 and 28, Discrete Math. 140 (1995), no. 1-3, 185-243.

Index entries for sequences related to Hadamard matrices

Crossrefs

Sequence in context: A246307 A269588 A048658 * A374961 A355022 A133079

Adjacent sequences: A001108 A001109 A001110 * A001112 A001113 A001114

Keyword

nonn,hard,nice,more

Author

N. J. A. Sloane

Extensions

a(8) from Brendan McKay, Feb 11 2012

Status

approved