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A110677 Numbers k such that the string 3333k is prime. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A107934 A155107 A126719 * A169640 A026051 A141818

Adjacent sequences:  A110674 A110675 A110676 * A110678 A110679 A110680

KEYWORD

nonn,base

AUTHOR

Parthasarathy Nambi, Sep 14 2005

STATUS

approved

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Last modified October 1 15:05 EDT 2020. Contains 337443 sequences. (Running on oeis4.)