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 A175668 #8 Mar 08 2019 03:30:37 %S A175668 4,11,1,12,1,16,7,7,17,5,4,20,4,3,1,10,12,1,13,28,18,1,3,4,4,1,1,2,32, %T A175668 25,13,4,4,3,1,2,4,14,4,12,23,3,16,5,9,3,9,4,4,2,34,7,15,9,3,4,4,4,4, %U A175668 4,10,4,14,4,5,24,17,43,7,38,14,4,9,1,4,4,10,4,28,4,14,4,14,4,4,10,4,10 %N A175668 First differences of A175648. %C A175668 Distance between twin semiprime pairs. %p A175668 A175648 := proc(n) option remember; if n = 1 then 6; else for a from procname(n-1)+1 do if numtheory[bigomega](a) = 2 and numtheory[bigomega](a+4) = 2 then return a; end if; end do: end if; end proc: %p A175668 A175668 := proc(n) A175648(n+1)-A175648(n) ; end proc: %p A175668 seq(A175668(n),n=1..100) ; # _R. J. Mathar_, Aug 07 2010 %Y A175668 Cf. A053319, A175612, A175648. %K A175668 nonn %O A175668 1,1 %A A175668 _Juri-Stepan Gerasimov_, Aug 05 2010 %E A175668 Terms from a(33) on corrected by _R. J. Mathar_, Aug 07 2010