A032709 Numbers k such that k prefixed by '9' and followed by '1' is prime.
1, 4, 7, 9, 15, 16, 18, 22, 24, 28, 31, 34, 37, 39, 42, 43, 46, 49, 51, 52, 55, 60, 63, 66, 72, 78, 79, 81, 85, 87, 90, 93, 94, 108, 112, 114, 115, 129, 133, 138, 141, 154, 157, 159, 162, 163, 169, 171, 177, 178, 180, 181, 184, 192, 195, 196, 204, 205, 211, 222
Offset: 1
Extensions
Offset changed by Andrew Howroyd, Aug 13 2024