A032728 Numbers k such that k prefixed by '3' and followed by '9' is prime.

4, 5, 7, 8, 10, 11, 16, 20, 22, 25, 29, 31, 32, 35, 38, 44, 46, 49, 52, 53, 55, 65, 70, 71, 73, 76, 77, 88, 91, 92, 98, 101, 103, 106, 107, 113, 115, 118, 121, 124, 125, 131, 137, 146, 148, 164, 169, 172, 176, 179, 184, 185, 200, 202, 205, 206, 208, 209, 211

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[250],PrimeQ[FromDigits[Join[{3},IntegerDigits[#],{9}]]]&] (* Harvey P. Dale, Aug 17 2021 *)

Extensions

Offset changed by Andrew Howroyd, Aug 13 2024