A188574 - OEIS

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A188574

Numbers n such that n^2 + 2*n + 2^n is prime.

%I #12 Jun 13 2017 13:46:56

%S 1,3,5,7,13,15,35,43,159,245,265,1573,1827,3359,3949,4615,5463,5919,

%T 19723

%N Numbers n such that n^2 + 2*n + 2^n is prime.

%t Select[Range[1, 10000, 2], PrimeQ[#^2 + 2 # + 2^#] &]

%o (PARI) is(n)=ispseudoprime(n^2+2*n+2^n) \\ _Charles R Greathouse IV_, Jun 13 2017

%Y Cf. A220425 (see the comment by _Jonathan Vos Post_).

%K nonn

%O 1,2

%A _Vincenzo Librandi_, Jan 07 2013

%E a(19) from _Bruno Berselli_, Jan 09 2013