A032727 Numbers k such that k prefixed by '2' and followed by '9' is prime.

2, 3, 6, 12, 17, 23, 26, 30, 33, 38, 39, 45, 53, 54, 57, 60, 65, 68, 69, 71, 72, 74, 78, 81, 87, 90, 93, 96, 99, 101, 105, 108, 113, 114, 116, 117, 126, 131, 137, 141, 149, 152, 155, 156, 158, 159, 164, 173, 179, 183, 185, 192, 203, 207, 210, 212, 215, 218, 222

Offset: 1

Author

Patrick De Geest, May 15 1998

Keywords

• nonn
• base

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A032702-A032733.

Programs

Mathematica

Select[Range[300],PrimeQ[FromDigits[Join[{2},IntegerDigits[#],{9}]]]&] (* Harvey P. Dale, Apr 02 2017 *)