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Exponents n such that 2^(2*n+1) - 3*2^n - 1 (A195461) is prime
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%I #29 Apr 09 2016 16:07:45

%S 2,3,4,5,8,16,27,28,33,36,48,66,90,112,508,1036,1041,1560,2208,2668,

%T 4388,6097,6517,11353,17284,22385,24740,29805,77188,135219,199237

%N Exponents n such that 2^(2*n+1) - 3*2^n - 1 (A195461) is prime

%C Obtained using a Lucas-Lehmer-type test due to Williams.

%C Next term > 200000.

%H H. C. Williams, <a href="http://projecteuclid.org/euclid.pjm/1102734270">A class of primality tests for trinomials which includes the Lucas-Lehmer test</a>, Pacific J. Math. Volume 98, Number 2 (1982), 477-494.

%o (PARI) for(n=1,10^9,if(ispseudoprime(2^(2*n+1) - 3*2^n - 1),print1(n,", "))); \\ _Joerg Arndt_, Apr 08 2016

%Y Cf. A195461.

%K nonn,more

%O 1,1

%A _Fabrice Lavier_, Jan 03 2016