Divisible design graphs with parameters $(4n,n+2,n-2,2,4,n)$ and $(4n,3n-2,3n-6,2n-2,4,n)$

Abstract

Divisible design graphs with parameters (4n, n + 2, n − 2, 2, 4, n)and (4n, 3n − 2, 3n − 6, 2n − 2, 4, n)