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%I #32 Jan 19 2020 09:35:04
%S 2,3,4,6,7,10,14,15,16,34,42,44,46,62,66,106,127,130,171,202,231,232,
%T 238,248,256,296,314,412,604,956,1023,1287,1454,1564,1766,2036,5215,
%U 5911,6092,9190,9916,10410,13456,14336,14444,15490,30835,32558,34770,41218
%N Numbers k such that 207*2^k + 1 is prime.
%H Jeppe Stig Nielsen, <a href="/A032480/b032480.txt">Table of n, a(n) for n = 1..68</a> (terms n = 1..66 from Robert Price)
%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 Ray Ballinger, <a href="http://www.prothsearch.com/index.html">Proth Search Page</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 f[n_]:=PrimeQ[207*2^n+1];lst={};Do[If[f[n],AppendTo[lst,n]],{n,7!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Mar 03 2010 *)
%t Select[Range[1000], PrimeQ[207*2^# + 1] & ] (* _Robert Price_, Dec 19 2018 *)
%o (PARI) is(n)=ispseudoprime(207*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017
%K nonn,hard
%O 1,1
%A _N. J. A. Sloane_
%E a(50)-a(66) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 19 2018
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