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A110675
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Numbers n such that the string 2222n is the decimal expansion of a prime number.
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1
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9, 47, 69, 89, 93, 123, 141, 147, 167, 177, 203, 219, 239, 243, 249, 251, 263, 273, 281, 287, 293, 309, 317, 321, 327, 333, 351, 377, 383, 387, 443, 477, 501, 503, 509, 527, 533, 537, 543, 567, 573, 579, 593, 599, 611, 617, 621, 629, 653, 659, 663, 683
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OFFSET
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1,1
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LINKS
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Harvey P. Dale, Table of n, a(n) for n = 1..1000
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EXAMPLE
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177 is in the sequence because 2222177 is prime.
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MATHEMATICA
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Select[Range[700], PrimeQ[FromDigits[Join[{2, 2, 2, 2}, IntegerDigits[ #]]]]&] (* Harvey P. Dale, Nov 14 2014 *)
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PROG
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(Magma) [ n: n in [1..700] | IsPrime(Seqint(Intseq(n) cat [2, 2, 2, 2])) ]; // Klaus Brockhaus, Feb 01 2011
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CROSSREFS
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Sequence in context: A250776 A054140 A307955 * A265805 A274270 A100790
Adjacent sequences: A110672 A110673 A110674 * A110676 A110677 A110678
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KEYWORD
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nonn,base
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AUTHOR
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Parthasarathy Nambi, Sep 14 2005
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STATUS
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approved
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