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A110677

Numbers k such that the string 3333k is prime.

1, 23, 31, 37, 41, 49, 67, 83, 97, 103, 119, 131, 133, 163, 199, 203, 217, 221, 233, 251, 257, 263, 277, 283, 301, 307, 311, 313, 331, 373, 383, 391, 397, 401, 419, 427, 431, 433, 439, 469, 481, 497, 509, 511, 527, 593, 601, 611, 619, 641

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OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..2500

EXAMPLE

k=103 is in the sequence because 3333k = 3333103 is prime.

MATHEMATICA

Select[Range[700], PrimeQ[FromDigits[Join[{3, 3, 3, 3}, IntegerDigits[#]]]] &] (* Vincenzo Librandi, Feb 03 2017 *)

PROG

(Magma) [n: n in [1..700] | IsPrime(Seqint(Intseq(n) cat [3, 3, 3, 3]))]; // Vincenzo Librandi, Feb 03 2017

CROSSREFS

Sequence in context: A356087 A155107 A126719 * A169640 A026051 A141818

Adjacent sequences: A110674 A110675 A110676 * A110678 A110679 A110680

KEYWORD

nonn,base

AUTHOR

Parthasarathy Nambi, Sep 14 2005

STATUS

approved

URL: https://oeis.org/A110677

⇱ A110677 - OEIS