A032707 Numbers k such that k prefixed by '7' and followed by '1' is prime.

0, 5, 6, 12, 15, 21, 32, 33, 35, 41, 45, 48, 54, 56, 59, 62, 68, 69, 74, 84, 90, 95, 101, 108, 116, 117, 119, 126, 134, 141, 147, 155, 167, 171, 174, 176, 182, 186, 188, 194, 197, 203, 209, 210, 216, 221, 222, 225, 227, 234, 242, 243, 246, 248, 255, 266

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

n71Q[n_]:=PrimeQ[FromDigits[Join[{7},IntegerDigits[n],{1}]]]; Select[ Range[ 0,300],n71Q] (* Harvey P. Dale, Jun 20 2017 *)

Extensions

Offset changed by Andrew Howroyd, Aug 11 2024