A217073 Numbers k such that (k^23-1)/(k-1) is prime.

10, 40, 82, 113, 127, 141, 170, 257, 275, 287, 295, 315, 344, 373, 442, 468, 609, 634, 646, 663, 671, 710, 819, 834, 857, 884, 894, 904, 992, 997, 1060, 1069, 1077, 1120, 1143, 1190, 1232, 1253, 1261, 1280, 1291, 1347, 1407, 1436, 1448, 1483, 1514, 1570, 1642

Offset: 1

Author

Tim Johannes Ohrtmann, Sep 26 2012

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A002384, A049409, A100330, A162862, A217070-A217089.

Programs

Magma

[n: n in [2..1700] |IsPrime((n^23 - 1) div (n - 1))]; // Vincenzo Librandi, Sep 28 2012

Mathematica

Select[Range[2, 1700], PrimeQ[(#^23 - 1)/(# - 1)] &] (* T. D. Noe, Sep 26 2012 *)

PARI

is(n)=isprime((n^23-1)/(n-1)) \\ Charles R Greathouse IV, Feb 17 2017

Extensions

More terms from T. D. Noe, Sep 26 2012