A110572 Numbers k such that the string 555k is prime.

7, 11, 29, 41, 47, 79, 89, 109, 119, 143, 167, 209, 221, 251, 253, 257, 277, 287, 293, 301, 307, 337, 349, 361, 383, 391, 419, 421, 439, 461, 487, 491, 521, 523, 557, 589, 593, 637, 661, 671, 677, 683, 691, 697, 707, 739, 743, 761, 767, 823, 827, 829, 853

Offset

1,1

Links

Table of n, a(n) for n=1..53.

Example

For k=143, concatenating 555 and k gives 555143 (prime).

Mathematica

Select[Range[853], PrimeQ[FromDigits[Join[{5, 5, 5}, IntegerDigits[#]]]]&] (* James C. McMahon, Apr 20 2024 *)

Crossrefs

Sequence in context: A122560 A136338 A193867 * A023254 A129807 A045461

Adjacent sequences: A110569 A110570 A110571 * A110573 A110574 A110575

Keyword

nonn,base

Author

Parthasarathy Nambi, Sep 12 2005

Extensions

More terms from Vincenzo Librandi, Mar 27 2010

Status

approved