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 A110680 Numbers k such that the string 4444k 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 k=109 is in the sequence because 4444k = 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 A350632 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 May 25 07:15 EDT 2024. Contains 372782 sequences. (Running on oeis4.)