1,11

The number of inequivalent maximal determinant {-1,1} matrices of order n where two matrices are considered equivalent if one can be obtained from the other by permuting rows, permuting columns and multiplying rows or columns by -1. Additional terms: a(20)=3, a(21)=7, a(24)=60, a(25)=78, a(28)=487. The terms a(4n) are given in sequence A007299.

J. H. E. Cohn, On the number of D-optimal designs, J. Combin. Theory Ser. A 66 (1994) 214-225.

Warren D. Smith, Studies in Computational Geometry Motivated by Mesh Generation, Ph. D. dissertation, Princeton University (1988).

J. Williamson, Determinants whose elements are 0 and 1, Amer. Math. Monthly 53 (1946) 427-434.

W. P. Orrick, On the enumeration of some D-optimal designs, preprint, 2005.

W. P. Orrick and B. Solomon, The Hadamard maximal determinant problem

E. Spence, Ted Spence's home page, website.

Cf. A003433, A007299.

Sequence in context: A046534 A131324 A079724 this_sequence A140750 A028264 A010122

Adjacent sequences: A111365 A111366 A111367 this_sequence A111369 A111370 A111371

hard,nonn

William P. Orrick (worrick(AT)indiana.edu), Nov 08 2005