Skew-Hadamard matrices of orders 188 and 388 exist
Abstract
Description
We construct several difference families on cyclic groups of orders 47 and 97, and use them to construct skew-Hadamard matrices of orders 188 and 388. Such difference families and matrices are constructed here for the first time. The matrices are constructed by using the Goethals-Seidel array.
7 pages, no figures, a paragraph added to the introduction, two misprints corrected. To appear in the International Mathematical Forum
7 pages, no figures, a paragraph added to the introduction, two misprints corrected. To appear in the International Mathematical Forum