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A032353 Numbers k such that 7*2^k+1 is prime.

%I A032353 #35 Feb 16 2025 08:32:36
%S A032353 2,4,6,14,20,26,50,52,92,120,174,180,190,290,320,390,432,616,830,1804,
%T A032353 2256,6614,13496,15494,16696,22386,54486,88066,95330,207084,283034,
%U A032353 561816,804534,811230,1491852,2139912,2167800,2915954,3015762,3511774,5775996
%N A032353 Numbers k such that 7*2^k+1 is prime.
%H A032353 Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</a>
%H A032353 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 A032353 Y. Gallot, <a href="http://www.utm.edu/research/primes/programs/gallot/index.html">Proth.exe: Windows Program for Finding Large Primes</a>
%H A032353 Wilfrid Keller, <a href="http://www.prothsearch.com/riesel2.html">List of primes k.2^n - 1 for k < 300</a>
%H A032353 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ProthPrime.html">Proth Prime</a>
%H A032353 <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 A032353 Select[Range[10^3], PrimeQ[7*2^# + 1] &] (* _Michael De Vlieger_, Feb 25 2017 *)
%o A032353 (PARI) is(n)=ispseudoprime(7*2^n+1) \\ _Charles R Greathouse IV_, Feb 20 2017
%o A032353 (Magma) [n: n in [1..830] | IsPrime(7*2^n+1)]; // _Arkadiusz Wesolowski_, Feb 24 2017
%Y A032353 Cf. A002255, A050527.
%K A032353 nonn,hard
%O A032353 1,1
%A A032353 _James R. Buddenhagen_
%E A032353 Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), _Joerg Arndt_, Apr 07 2013
%E A032353 a(41) from _Jeppe Stig Nielsen_, Jul 25 2019