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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
OFFSET
1,2
LINKS
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
KEYWORD
nonn,base
AUTHOR
Parthasarathy Nambi, Sep 14 2005
STATUS
approved