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 A176171 #2 Mar 31 2012 12:38:35
%S A176171 3,3,3,3,3,3,3,3,3,5,3,3,3,5,3,3,3,3,5,5,3,3,3,3,3,3,5,5,3,5,3,3,3,3,
%T A176171 5,3,3,5,3,3,3,5,3,3,3,5,7,3,5,3,5,3,5,5,3,5,3,3,3,3,5,3,3,5,3,3,5,3,
%U A176171 5,7,3,3,3,5,3,3,5,3,3,7,3,3,5,7,5,3,5,3,3,7,3,5,3,5,3,3,5,5,3,5,3,5,3,3,3
%N A176171 Second prime-factor of n-th product of 4 distinct primes.
%C A176171 FactorInteger[210]=2*3*5*7,...
%t A176171 f0[n_]:=Last/@FactorInteger[n]=={1,1,1,1};f1[n_]:=Min[First/@FactorInteger[n]];f2[n_]:=First/@FactorInteger[n][[2,1]];f3[n_]:=First/@FactorInteger[n][[3,1]];f4[n_]:=Max[First/@FactorInteger[n]];lst={};Do[If[f0[n],AppendTo[lst,f2[n]]],{n,0,2*7!}];lst
%Y A176171 Cf. A006881, A007304, A070647, A096916, A096917, A096918, A096919, A176170
%K A176171 nonn
%O A176171 1,1
%A A176171 _Vladimir Joseph Stephan Orlovsky_, Apr 10 2010