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A175731 Semiprimes m such that either 2m-1 or 2m+1 is prime, but not both. 0

%I

%S 4,10,14,22,26,33,34,35,39,49,55,57,65,74,82,86,87,91,95,106,111,115,

%T 119,121,129,134,142,146,155,158,159,166,169,177,183,187,194,201,205,

%U 209,215,217,219,221,249,254,262,274,278,289,299,301,303,323,326,327,329,339,341

%N Semiprimes m such that either 2m-1 or 2m+1 is prime, but not both.

%C The "or" is exclusive. [From _D. S. McNeil_, Aug 25 2010]

%e a(1)=4 because 2*4-1=7=prime and 2*4+1=9=nonprime.

%Y Cf. A000040, A001358.

%K nonn

%O 1,1

%A _Juri-Stepan Gerasimov_, Aug 24 2010

%E Corrected (15 removed) by _R. J. Mathar_, Aug 25 2010. Also corrected by D. S. McNeil.

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Last modified January 23 14:45 EST 2021. Contains 340385 sequences. (Running on oeis4.)