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A050894 Numbers n such that 271*2^n-1 is prime. 0

%I #18 Jan 17 2019 10:08:17

%S 1,7,21,55,175,235,2289,12419,19917,19971,21979,54007,66241,68757,

%T 98595,241211,274509,322971,342349,470529

%N Numbers n such that 271*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(271*2^n-1) \\ _Charles R Greathouse IV_, Jun 13 2017

%K hard,nonn

%O 1,2

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

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

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Last modified March 28 08:22 EDT 2024. Contains 371236 sequences. (Running on oeis4.)