%I #29 Dec 23 2024 13:35:05

%S 3,4,9,60,72,75,84,348,592,1348,1380,1632,1855,2335,4528,9813,17103,

%T 28935,34023,100459,243544,281865,371844,648792,812035,886480,2080464,

%U 4146003

%N Numbers k such that 201*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 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>

%t Select[Range[1000], PrimeQ[201*2^# + 1] & ] (* _Robert Price_, Dec 19 2018 *)

%o (PARI) is(n)=ispseudoprime(201*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%K nonn,hard,more

%O 1,1

%A _N. J. A. Sloane_.

%E a(20)-a(26) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 19 2018

%E a(27) from _Jeppe Stig Nielsen_, May 30 2020

%E a(28) from _Jeppe Stig Nielsen_, Dec 23 2024