On a new class of productive regular Hadamard matrices

Abstract: We show that for each integer n for which there is a Hadamard matrix of order and is a prime number, there is a productive regular Hadamard matrix of order . As a corollary, by applying a recent result of Ionin, we get many parametrically new classes of symmetric designs whenever either of or is a prime power. [Copyright &y& Elsevier]