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 A176406 #7 Feb 03 2019 22:28:15
%S A176406 7,13,19,23,31,33,37,47,49,53,55,63,67,75,83,85,89,91,93,109,113,117,
%T A176406 119,121,127,131,139,141,143,153,157,159,167,175,181,183,185,199,201,
%U A176406 203,207,211,213,215,217,219,233,235,245,247,251,257,263,265,285,287
%N A176406 Odd semiprimes minus 2.
%F A176406 a(n) = A046315(n) - 2.
%p A176406 isA001358 := proc(n) numtheory[bigomega](n) = 2 ; end proc: for n from 1 to 400 by 2 do if isA001358(n+2) then printf("%d,",n) ; end if; end do: # _R. J. Mathar_, Apr 20 2010
%t A176406 Select[Range[9,301,2],PrimeOmega[#]==2&]-2 (* _Harvey P. Dale_, May 11 2018 *)
%Y A176406 Cf. A007921.
%K A176406 nonn
%O A176406 1,1
%A A176406 _Juri-Stepan Gerasimov_, Apr 16 2010
%E A176406 Entries checked by _R. J. Mathar_, Apr 20 2010