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

1,1

Comments

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

Links

Table of n, a(n) for n=1..105.

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

Crossrefs

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

Sequence in context: A335465 A079083 A381042 * A032568 A053388 A372511

Adjacent sequences: A176168 A176169 A176170 * A176172 A176173 A176174

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Apr 10 2010

Status

approved