A110680 Numbers k such that the string 4444k is prime.

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

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