A032725 Numbers k such that k prefixed by '9' and followed by '7' is prime.

0, 3, 4, 6, 7, 9, 12, 13, 15, 18, 22, 25, 27, 33, 37, 39, 43, 46, 49, 54, 58, 67, 69, 76, 78, 81, 85, 88, 90, 96, 109, 112, 123, 129, 136, 138, 139, 145, 157, 175, 180, 183, 186, 195, 196, 199, 207, 210, 217, 222, 223, 229, 231, 234, 235, 237, 238, 246, 250, 255

Offset

1,2

Links

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

Mathematica

Select[Range[0, 300], PrimeQ[FromDigits[Join[{9}, IntegerDigits[#], {7}]]]&] (* Harvey P. Dale, Mar 01 2025 *)

Crossrefs

Cf. A032702-A032733.

Sequence in context: A338387 A360799 A136110 * A089038 A336175 A380049

Adjacent sequences: A032722 A032723 A032724 * A032726 A032727 A032728

Keyword

nonn,base

Author

Patrick De Geest, May 15 1998

Extensions

Offset changed by Andrew Howroyd, Aug 13 2024

Status

approved