|
%I #23 Jan 17 2019 10:08:17
%S 1,3,7,15,43,57,61,75,145,217,247,2803,3403,4375,5113,9883,14565,
%T 17397,65977,82081,92517,214453,248055,369535,969795
%N Numbers k such that 79*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>
%H Kosmaj, <a href="http://www.15k.org/riesellist.html">Riesel list k<300</a>.
%t Select[Range[1000], PrimeQ[79*2^# - 1] & ] (* _Robert Price_, Dec 22 2018 *)
%o (PARI) is(n)=ispseudoprime(79*2^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017
%K hard,nonn,more
%O 1,2
%A _N. J. A. Sloane_, Dec 29 1999
%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008
%E a(25) from the Wilfrid Keller link by _Robert Price_, Dec 22 2018
|
