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A122721 Numbers n such that abs(7^n - 2^11) is prime. 0

%I

%S 2,4,5,6,9,21,41,52,58,118,130,585,614,744,881,941,966,1280,1658,4985

%N Numbers n such that abs(7^n - 2^11) is prime.

%H C. Pomerance, <a href="http://www.sciencenews.org/pages/sn_arc98/7_4_98/mathland.htm">Science News reference</a>.

%e For x = 2 abs(7^2-2^11) = 1999 which is prime. So 2 is the first entry.

%o (PARI) g(n) = for(x=1,n,y=abs(7^x-2^11);if(ispseudoprime(y),print1(x",")))

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, Sep 23 2006

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Last modified October 14 18:28 EDT 2019. Contains 328022 sequences. (Running on oeis4.)