A032721 n prefixed by '4' and followed by '7' is a prime.

5, 6, 8, 12, 15, 17, 21, 29, 32, 33, 35, 39, 44, 45, 50, 51, 54, 56, 59, 63, 65, 78, 81, 87, 93, 95, 96, 98, 101, 104, 105, 107, 111, 117, 122, 125, 135, 138, 146, 150, 159, 161, 162, 164, 168, 173, 177, 188, 189, 192, 194, 195, 201, 215, 218, 219, 222, 225

Offset

0,1

Links

Harvey P. Dale, Table of n, a(n) for n = 0..1000

Mathematica

Select[Range[300], PrimeQ[FromDigits[Join[{4}, IntegerDigits[#], {7}]]]&] (* Harvey P. Dale, Jan 08 2019 *)

Crossrefs

Sequence in context: A047321 A033158 A193569 * A105106 A140504 A120131

Adjacent sequences: A032718 A032719 A032720 * A032722 A032723 A032724

Keyword

nonn,base

Author

Patrick De Geest, May 15 1998

Status

approved