A067936 Let rep(n) be the n-th repunit number, sequence gives values of n such that : rep(n) == rep(3) (mod n).

1, 2, 3, 4, 5, 6, 8, 10, 11, 12, 15, 20, 21, 24, 25, 30, 33, 39, 40, 50, 51, 55, 57, 60, 69, 75, 87, 93, 100, 105, 111, 120, 123, 125, 129, 141, 150, 159, 165, 177, 183, 195, 200, 201, 213, 219, 222, 231, 237, 249, 250, 267, 273, 275, 291, 300, 303, 309, 321, 327