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A110055
Numbers n such that the string 333n is the decimal expansion of a prime number.
1
1, 11, 17, 29, 31, 43, 47, 49, 53, 59, 77, 91, 101, 103, 107, 131, 139, 161, 187, 197, 209, 227, 233, 253, 269, 271, 283, 287, 299, 323, 331, 337, 341, 349, 367, 383, 397, 419, 427, 433, 439, 449, 451, 457, 479, 491, 493, 497, 503, 517, 533, 539, 563, 581
OFFSET
1,2
LINKS
EXAMPLE
1 is in the sequence because 3331 is prime.
59 is in the sequence because 33359 is prime.
107 is in the sequence because 333107 is prime.
MATHEMATICA
Select[Range[1000], PrimeQ[FromDigits[Join[{3, 3, 3}, IntegerDigits[ # ]]]] &] (Delarte)
Select[Range[1000], PrimeQ[333*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Jun 03 2023 *)
PROG
(Magma) [ n: n in [1..600] | IsPrime(Seqint(Intseq(n) cat [3, 3, 3])) ]; // Klaus Brockhaus, Feb 03 2011
CROSSREFS
Sequence in context: A120139 A191061 A377177 * A240095 A105886 A225493
KEYWORD
nonn,base
AUTHOR
Parthasarathy Nambi, Sep 04 2005
EXTENSIONS
More terms from Alonso del Arte, Sep 06 2005
STATUS
approved