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%I #31 May 11 2023 14:47:08
%S 1,3,9,15,21,33,2007,2127,3759,29355,34653,57285,99069,1933695
%N Numbers n such that 2^n + n^2 is prime.
%C Values 2^2007+2007^2, 2^2127+2127^2, 2^3759+3759^2 were proved prime with Primo.
%C n is always an odd multiple of 3 (except for the first term), i.e., a(n) is a subsequence of A016945. - _Lekraj Beedassy_, Jan 01 2007
%C Some of the results were computed using the PrimeFormGW (PFGW) primality-testing program. - _Hugo Pfoertner_, Nov 14 2019
%D J.-M. De Koninck & A. Mercier, 1001 Problemes en Theorie Classique Des Nombres, Problem 165 pp. 30, 160, Ellipses Paris 2004.
%H Henri Lifchitz, Renaud Lifchitz, <a href="http://www.primenumbers.net/prptop/searchform.php?form=2%5En%2Bn%5E2">PRP Top Records.</a> 2^n+n^2.
%o (PARI) for(n=1,5000, if(isprime(2^n+n^2),print(n)))
%Y Cf. A001580, A016945, A061119, A072180, A094133.
%K nonn,more,hard
%O 1,2
%A _Jason Earls_, Oct 16 2001
%E a(10)-a(13) from _Hugo Pfoertner_, Jun 26 2004
%E a(14) from _Ryan Propper_, May 11 2023. n=1933695 corresponds to a probable prime with 582101 digits, and was PRP tested with PFGW.
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