login
Numbers k such that 25*2^k+1 is prime.
2

%I #35 Oct 13 2019 02:58:45

%S 2,4,6,10,20,22,52,64,78,184,232,268,340,448,554,664,740,748,1280,

%T 1328,1640,3314,3904,3938,5152,9522,57488,66872,148060,154254,216092,

%U 302194,367294,627710,966414,1211488,1258562,1298186,2141884,2583690,2927222,3733144

%N Numbers k such that 25*2^k+1 is prime.

%H Jeppe Stig Nielsen, <a href="/A032362/b032362.txt">Table of n, a(n) for n = 1..43</a>

%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(25*2^n+1) \\ _Charles R Greathouse IV_, Jun 06 2017

%K nonn,hard

%O 1,1

%A _James R. Buddenhagen_

%E Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), _Joerg Arndt_, Apr 07 2013

%E a(40)-a(42) from _Jeppe Stig Nielsen_, Sep 21 2019