A059109 n*phi(n)-1 is prime, where phi is the Euler function (A000010).

3, 4, 5, 6, 7, 8, 9, 11, 12, 14, 16, 17, 18, 21, 24, 25, 26, 29, 30, 31, 33, 35, 36, 38, 42, 47, 54, 61, 63, 65, 66, 67, 71, 74, 75, 78, 81, 87, 91, 97, 99, 101, 105, 117, 119, 121, 123, 127, 128, 131, 132, 135, 139, 140, 143, 144, 147, 149, 154, 156, 158, 162, 172