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Numbers n such that 25*2^n-1 is prime.
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%I #18 Jan 17 2019 10:08:17

%S 3,9,11,17,23,35,39,75,105,107,155,161,215,225,335,635,651,687,1479,

%T 1515,1953,2435,2963,3671,5979,7551,8091,9791,15015,20897,26279,43371,

%U 130407,587585,716769,942563

%N Numbers n such that 25*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(25*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