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A357934 Products of two distinct lesser twin primes A001359.

%I A357934 #22 Feb 13 2025 07:40:35
%S A357934 15,33,51,55,85,87,123,145,177,187,205,213,295,303,319,321,355,411,
%T A357934 447,451,493,505,535,537,573,591,649,681,685,697,717,745,781,807,843,
%U A357934 895,933,955,985,1003,1041,1111,1135,1177,1189,1195,1207,1257,1293,1345,1383,1405,1507,1555,1563
%N A357934 Products of two distinct lesser twin primes A001359.
%H A357934 R. J. Mathar, <a href="/A357934/b357934.txt">Table of n, a(n) for n = 1..10000</a>
%p A357934 omega := proc(n)
%p A357934     nops(numtheory[factorset](n)) ;
%p A357934 end proc:
%p A357934 isA357934 := proc(n)
%p A357934     local pe,p,q;
%p A357934     if numtheory[bigomega](n)= 2 and omega(n) =2 then
%p A357934         pe := ifactors(n)[2] ;
%p A357934         p := op(1,op(1,pe)) ;
%p A357934         q := op(1,op(2,pe)) ;
%p A357934         if isprime(p+2) and isprime(q+2) then
%p A357934             true;
%p A357934         else
%p A357934             false;
%p A357934         end if;
%p A357934     else
%p A357934         false;
%p A357934     end if;
%p A357934 end proc:
%p A357934 for n from 10 to 2000 do
%p A357934     if isA357934(n) then
%p A357934         printf("%d,",n) ;
%p A357934     end if;
%p A357934 end do: # _R. J. Mathar_, Feb 13 2025
%t A357934 d = {};less = Select[Range[1607], PrimeQ[#] && PrimeQ[# + 2] &];Do[Do[AppendTo[d, less[[m]] less[[n]]], {m, n + 1, Length[less]}], {n,
%t A357934   1, Length[less] - 1}]; Take[Sort[d], 55]
%o A357934 (PARI) list(lim)=my(v=List(),p=5); forprime(q=7,lim\3+2, if(q-p==2, my(r=3); forprime(s=5,min(lim\p+2,p), if(s-r==2, listput(v, p*r)); r=s)); p=q); Set(v) \\ _Charles R Greathouse IV_, Oct 21 2022
%Y A357934 Cf. A001359. Subsequence of A006881.
%K A357934 nonn
%O A357934 1,1
%A A357934 _Artur Jasinski_, Oct 21 2022