A102498 - OEIS

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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

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OFFSET

0,1

LINKS

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

EXAMPLE

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

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

MATHEMATICA

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

CROSSREFS

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

Sequence in context: A363482 A058030 A347344 * A019399 A255581 A061967

Adjacent sequences: A102495 A102496 A102497 * A102499 A102500 A102501

KEYWORD

easy,nonn,base

AUTHOR

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

STATUS

approved