The OEIS is supported by the many generous donors to the OEIS Foundation.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
%I #13 Jan 26 2025 14:17:57
%S 3,45,90,180,255,615,705,1350,1770,3225,5295,5775,5955,6060,8580,9855,
%T 9945,11175,13095,13740,15195,21825,26820,26925,27615,28920,30075,
%U 30705,31710,33375,35700,37350,37665,41250,43770,49185,50700,52185,53640
%N Numbers k for which 2*k-1, 4*k-1, 8*k-1 and 16*k-1 are primes.
%H Amiram Eldar, <a href="/A124494/b124494.txt">Table of n, a(n) for n = 1..10000</a>
%t Select[3*Range[20000], And @@ PrimeQ /@ ({2, 4, 8, 16}*# - 1) &] (* _Ray Chandler_, Nov 22 2006 *)
%Y Cf. A006254, A124485, A125113, A124514, A124515, A124516.
%Y Subsequence of A124493. Supersequence of A124017.
%K nonn,changed
%O 1,1
%A _Artur Jasinski_, Nov 04 2006
%E Extended by _Ray Chandler_, Nov 22 2006