On the number of \(D\)-optimal designs
The main result of the paper is the theorem: For \(n=18\), there are precisely three essentially different matrices with elements \(\pm 1\) having the maximum determinant. Only one of these is of the circulant type, but all are of the skew type. This means that there are three \(D\)-optimal designs for \(n=18\).
scientific article; zbMATH DE number 599873