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A053355 Numbers k such that 277*2^k + 1 is prime. 0

%I #28 Sep 08 2022 08:45:00

%S 2,6,8,18,20,22,36,62,108,120,162,180,222,450,530,706,1028,1200,1296,

%T 1362,2280,3788,7130,8082,8150,10226,10302,11578,48426,57890,73890,

%U 139346,201378,225322,1134740,1584740,1634878,1728302,1880022,2340182

%N Numbers k such that 277*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[277*2^# + 1] &] (* _G. C. Greubel_, May 24 2018 *)

%o (PARI) is(n)=ispseudoprime(277*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017

%o (Magma) [n: n in [1..300] | IsPrime(277*2^n+1)]; // _G. C. Greubel_, May 24 2018

%K hard,nonn,more

%O 1,1

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

%E a(31)-a(39) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 20 2018

%E a(40) from _Jeppe Stig Nielsen_, Apr 04 2020

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Last modified March 28 13:42 EDT 2024. Contains 371254 sequences. (Running on oeis4.)