A110675 Numbers n such that the string 2222n is the decimal expansion of a prime number.

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

Offset

1,1

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

177 is in the sequence because 2222177 is prime.

Mathematica

Select[Range[700], PrimeQ[FromDigits[Join[{2, 2, 2, 2}, IntegerDigits[ #]]]]&] (* Harvey P. Dale, Nov 14 2014 *)

Prog

(Magma) [ n: n in [1..700] | IsPrime(Seqint(Intseq(n) cat [2, 2, 2, 2])) ]; // Klaus Brockhaus, Feb 01 2011

Crossrefs

Sequence in context: A054140 A370622 A307955 * A265805 A274270 A100790

Adjacent sequences: A110672 A110673 A110674 * A110676 A110677 A110678

Keyword

nonn,base

Author

Parthasarathy Nambi, Sep 14 2005

Status

approved