See the matrices? How many primes? p = 3; nmats = 6; p = 5; nmats = 12; p = 7; nmats = 18; p = 11; nmats = 30; p = 13; nmats = 38; p = 17; nmats = 52; p = 19; nmats = 58; p = 23; nmats = 74; p = 29; nmats = 96; p = 31; nmats = 106; p = 37; nmats = 128; p = 41; nmats = 146; p = 43; nmats = 154; p = 47; nmats = 170; p = 53; nmats = 196; p = 59; nmats = 222; p = 61; nmats = 230; p = 67; nmats = 258; p = 71; nmats = 274; p = 73; nmats = 284; p = 79; nmats = 310; p = 83; nmats = 330; p = 89; nmats = 358; p = 97; nmats = 392;