A053361 - OEIS

%I #31 Dec 21 2024 02:35:55

%S 10,22,34,42,150,1758,6706,11634,18502,52614,102150,194830,207546,

%T 252858,333406,638902,989182,1117182,1317378,1522650,4911870

%N Numbers k such that 289*2^k + 1 is prime.

%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[5*10^3], PrimeQ[289*2^# + 1] &] (* _G. C. Greubel_, May 25 2018 *)

%o (PARI) is(n)=ispseudoprime(289*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%o (Magma) [n: n in [1..3000] | IsPrime(289*2^n+1)];  // _G. C. Greubel_, May 25 2018

%K hard,nonn,more

%O 1,1

%A _N. J. A. Sloane_, Dec 29 1999

%E a(11)-a(20) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 22 2018

%E a(21) from _Jeppe Stig Nielsen_, Dec 20 2024