A176171 Second prime-factor of n-th product of 4 distinct primes.

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, 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, 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

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Apr 10 2010

Keywords

• nonn

Comments

FactorInteger[210]=2*3*5*7,...

Crossrefs

Cf. A006881, A007304, A070647, A096916, A096917, A096918, A096919, A176170

Programs

Mathematica

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