A032702 n prefixed by '2' and followed by '1' is a prime.

1, 4, 5, 7, 8, 11, 13, 14, 16, 22, 25, 28, 31, 34, 35, 37, 38, 41, 44, 52, 53, 55, 59, 62, 67, 71, 73, 74, 79, 80, 85, 86, 97, 100, 101, 103, 106, 110, 112, 119, 121, 122, 134, 139, 140, 148, 149, 152, 160, 161, 166, 170, 175, 182, 184, 185, 187, 188, 191, 196