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%I #22 Dec 20 2018 14:03:04
%S 8,9,24,32,71,117,141,144,369,393,575,837,921,1007,3825,3837,18813,
%T 21731,25233,36261,57104,128301,299840,404379,714200,717731,910544,
%U 1061853,1658303
%N Numbers k such that 171*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[171*2^# + 1] & ] (* _Robert Price_, Dec 18 2018 *)
%o (PARI) is(n)=ispseudoprime(171*2^n+1) \\ _Charles R Greathouse IV_, Jun 13 2017
%K nonn,hard,more
%O 1,1
%A _N. J. A. Sloane_.
%E a(22)-a(29) from the Ray Ballinger and Wilfrid Keller link by _Robert Price_, Dec 18 2018