A102498 Values of n for which the concatenation 3nn3 (from sequence A100896) are primes.

13, 23, 28, 29, 38, 43, 49, 50, 52, 56, 64, 67, 80, 83, 92, 94, 95, 97, 1000, 1003, 1024, 1025, 1028, 1039, 1046, 1048, 1051, 1058, 1063, 1072, 1073, 1075, 1084, 1087, 1091, 1096, 1103, 1109, 1114, 1117, 1130, 1136, 1145, 1154, 1168, 1189, 1192

Offset: 0

Author

Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 13 2005

Keywords

• easy
• nonn
• base

Examples

			The number 313133 is prime and corresponds to n=13.
The number 3100010003 is prime and corresponds to n=1000.
		

Links

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

Crossrefs

The full sequence of integers of the form 3nn3 is A100896. The primes the correspond to these values of n are sequence A102499.

Programs

Mathematica

Select[Range[1200],PrimeQ[FromDigits[Join[{3},IntegerDigits[#], IntegerDigits[ #],{3}]]]&] (* Harvey P. Dale, Dec 24 2012 *)