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A173416 Exactly one of 2n^2-1 and 2n^2+1 is prime. 0

%I

%S 1,2,4,7,8,9,10,11,13,15,17,18,22,25,27,28,30,33,34,38,39,41,43,46,49,

%T 50,52,56,59,62,63,64,66,69,72,73,75,76,80,81,85,91,92,93,95,96,98,99,

%U 105,108,109,112,113,115,118,123,125,126,127,134,135,137,140,141,143

%N Exactly one of 2n^2-1 and 2n^2+1 is prime.

%C Numbers in A089001 or in A066049 but not in both. [From _R. J. Mathar_, Mar 09 2010]

%e a(1)=1 because 2*1^2-1=1 is nonprime and 2*1^2+1=3 is prime.

%K nonn

%O 1,2

%A _Juri-Stepan Gerasimov_, Mar 01 2010

%E 37 removed by _R. J. Mathar_, Mar 09 2010

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Last modified April 9 04:05 EDT 2020. Contains 333343 sequences. (Running on oeis4.)