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Products pq ("semiprimes") of two primes p and q >= p such that q+2 is a prime.
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%I #3 Mar 30 2012 16:50:46

%S 6,9,10,15,22,25,33,34,51,55,58,77,82,85,87,118,119,121,123,142,145,

%T 177,187,202,203,205,213,214,221,274,287,289,295,298,303,319,321,355,

%U 358,377,382,394,411,413,447,451,454,478,493,497,505,533,535,537,538,551,562,573

%N Products pq ("semiprimes") of two primes p and q >= p such that q+2 is a prime.

%p p:=ithprime;

%p t1:=[];

%p for i from 1 to 100 do

%p p1:=p(i);

%p for j from i to 100 do

%p p2:=p(j);

%p if isprime(p2+2) then t1:=[op(t1),p1*p2]; fi;

%p od: od:

%p t2:=sort(t1);

%Y Cf. A108605.

%K nonn

%O 1,1

%A _N. J. A. Sloane_, Oct 17 2009