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%I #2 Mar 31 2012 12:38:35
%S 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 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 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 Second prime-factor of n-th product of 4 distinct primes.
%C FactorInteger[210]=2*3*5*7,...
%t 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 Cf. A006881, A007304, A070647, A096916, A096917, A096918, A096919, A176170
%K nonn
%O 1,1
%A _Vladimir Joseph Stephan Orlovsky_, Apr 10 2010
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