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A157353 Products (semiprimes) of two distinct primes that are not safe primes. 4

%I #12 Jan 22 2021 02:12:59

%S 6,26,34,38,39,51,57,58,62,74,82,86,87,93,106,111,122,123,129,134,142,

%T 146,158,159,178,183,194,201,202,206,213,218,219,221,226,237,247,254,

%U 262,267,274,278,291,298,302,303,309,314,323,326,327,339,346,362,377

%N Products (semiprimes) of two distinct primes that are not safe primes.

%e 6=2*3; 2 and 3 are not safe primes.

%e 26=2*13; 2 and 13 are not safe primes.

%t lst={};Do[If[Plus@@Last/@FactorInteger[n]==2,a=Length[First/@FactorInteger[n]];If[a==2,b=First/@FactorInteger[n];c=b[[1]];d=b[[2]];If[ !PrimeQ[(c-1)/2]&&!PrimeQ[(d-1)/2],AppendTo[lst,n]]]],{n,7!}];lst

%Y Cf. A001358, A005384, A005385, A006881, A007304, A111206, A157342, A157344, A157345, A157346, A157347, A157352.

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Feb 27 2009

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