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A110675 Numbers n such that the string 2222n is the decimal expansion of a prime number. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A250776 A054140 A307955 * A265805 A274270 A100790

Adjacent sequences:  A110672 A110673 A110674 * A110676 A110677 A110678

KEYWORD

nonn,base

AUTHOR

Parthasarathy Nambi, Sep 14 2005

STATUS

approved

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Last modified September 25 06:05 EDT 2020. Contains 337335 sequences. (Running on oeis4.)