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A110680 Numbers n such that the string 4444n is prime. 2
9, 21, 43, 49, 61, 63, 69, 73, 87, 109, 127, 147, 159, 169, 171, 201, 207, 213, 217, 229, 241, 261, 289, 291, 331, 339, 357, 369, 381, 397, 409, 469, 471, 483, 487, 507, 519, 549, 591, 607, 621, 639, 663, 669, 697, 703, 711, 717, 729, 747 (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

n=109 is in the sequence because 4444n = 4444109  is prime.

MATHEMATICA

Select[Range[800], PrimeQ[4444*10^IntegerLength[#]+#]&] (* Harvey P. Dale, Jul 04 2014 *)

CROSSREFS

Sequence in context: A184040 A242990 A053476 * A163205 A154862 A020137

Adjacent sequences:  A110677 A110678 A110679 * A110681 A110682 A110683

KEYWORD

nonn,base

AUTHOR

Parthasarathy Nambi, Sep 14 2005

STATUS

approved

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Last modified November 22 18:55 EST 2019. Contains 329410 sequences. (Running on oeis4.)