login
Numbers k such that 315*2^k+1 is prime.
1

%I #17 Jan 05 2020 02:25:33

%S 1,3,6,9,20,22,27,32,72,97,99,104,107,120,140,142,151,180,304,305,342,

%T 440,489,521,635,665,673,767,876,1040,1313,1359,1764,2032,2224,2280,

%U 2783,2832,2875,5256,8225,10297,11124,12124,17552,18592,24435,30704,37467

%N Numbers k such that 315*2^k+1 is prime.

%H Jeppe Stig Nielsen, <a href="/A322949/b322949.txt">Table of n, a(n) for n = 1..77</a> (terms n = 1..74 from Robert Price)

%H Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</a>

%H Ray Ballinger and Wilfrid Keller, <a href="http://www.prothsearch.com/riesel1a.html">List of primes k.2^n + 1 for 300 < k < 600</a>

%H Y. Gallot, <a href="http://www.utm.edu/research/primes/programs/gallot/index.html">Proth.exe: Windows Program for Finding Large Primes</a>

%H Wilfrid Keller, <a href="http://www.prothsearch.com/riesel2.html">List of primes k.2^n - 1 for k < 300</a>

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/ProthPrime.html">Proth Prime</a>

%H <a href="/index/Pri#riesel">Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime</a>

%t Select[Range[1000], PrimeQ[315*2^# + 1] &] (* _Robert Price_, Dec 31 2018 *)

%Y Cf. A002255, A050527.

%K nonn,hard

%O 1,2

%A _Robert Price_, Dec 31 2018