A175168 - OEIS

%I #15 Jun 27 2024 10:20:26

%S 6,10,14,22,26,27,30,34,38,45,46,58,62,74,82,86,94,106,118,122,134,

%T 142,146,153,155,158,166,170,178,182,189,194,202,206,214,215,218,226,

%U 231,254,262,274,278,287,297,298,302,314,323

%N Numbers k such that 2^(k-1) mod k is a prime number.

%C Numbers k such that A062173(k) is prime.

%H Harvey P. Dale, <a href="/A175168/b175168.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[323], PrimeQ[Mod[2^(#-1), #]] &]

%t Select[Range[350], PrimeQ[PowerMod[2,#-1,#]]&] (* _Harvey P. Dale_, Jun 07 2016 *)

%Y Cf. A000040, A062173.

%K nonn

%O 1,1

%A _Juri-Stepan Gerasimov_, Dec 02 2010