A032405 - OEIS

%I #31 Dec 23 2024 10:04:45

%S 1,4,28,32,44,47,71,128,137,193,676,2344,7828,10883,21596,31724,47783,

%T 49816,61300,212396,415412,2382772,2841992,4091044

%N Numbers k such that 111*2^k+1 is prime.

%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/riesel1.html">List of primes k.2^n + 1 for k < 300</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 <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>

%o (PARI) is(n)=ispseudoprime(111*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn

%O 1,2

%A _James R. Buddenhagen_

%E a(20)-a(21) from http://www.prothsearch.com/riesel1.html by _Robert Price_, Dec 14 2018

%E a(22)-a(23) from _Jeppe Stig Nielsen_, Jan 19 2020

%E a(24)