This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A255746 #17 Jul 15 2015 20:27:31
%S A255746 6,10,22,34,35,51,58,65,82,87,91,111,115,118,119,129,141,142,155,183,
%T A255746 201,202,205,209,213,214,215,217,249,274,287,291,295,298,299,301,305,
%U A255746 319,323,335,358,377,382,391,394,403,407,411,413,447,454,469,478,481
%N A255746 Squarefree semiprimes n such that n+4 is also a squarefree semiprime.
%C A255746 Conjecturally, the sequence is infinite.
%H A255746 Peter J. C. Moses, <a href="/A255746/b255746.txt">Table of n, a(n) for n = 1..1000</a>
%F A255746 A000005(a(n)) = A000005(a(n)+4) = 4.
%e A255746 65 = 5*13; 65 + 4 = 69 = 3*23. So 65 is in the sequence.
%t A255746 Select[Range@ 500, And[SquareFreeQ@ #, PrimeOmega@ # == 2, SquareFreeQ[# + 4], PrimeOmega[# + 4] == 2] &] (* _Michael De Vlieger_, Jul 12 2015 *)
%o A255746 (PARI) main(size)={ v=vector(size); i=0; m=1; while(i<size, if(omega(m)==2&&omega(m+4)==2&&issquarefree(m)&&issquarefree(m+4),v[i++]=m);m++;); return(v);} /* _Anders Hellström_, Jul 11 2015 */
%Y A255746 Cf. A000005, A001358, A005117, A175648.
%K A255746 nonn
%O A255746 1,1
%A A255746 _Vladimir Shevelev_, Jul 11 2015
%E A255746 More terms from _Peter J. C. Moses_, Jul 11 2015