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Numbers n such that 197*2^n-1 is prime.
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%I #18 Jan 17 2019 10:08:17

%S 2,16,20,22,40,82,112,178,230,302,304,328,374,442,472,500,580,694,

%T 1264,1634,1784,3080,5722,7174,8908,18502,18746,39094,99338,170066,

%U 202534,325610,510940,569222,635042,825188

%N Numbers n such that 197*2^n-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>.

%o (PARI) is(n)=ispseudoprime(197*2^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017

%K hard,nonn

%O 1,1

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

%E More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008