A073753 a(n) = A073752(A073752(n)), where A073752(n) = gcd(n/spf(n), n/gpf(n)), with spf(n) as the smallest and gpf(n) as the greatest prime factor of n (see A020639, A006530).

1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 3, 1, 1, 1, 1, 8, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 1, 3, 1, 2, 1, 1, 1, 1, 1, 1, 1, 16, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 4, 9, 1, 1, 1, 1, 1, 1, 2, 1, 3, 1, 1, 1, 1, 1, 8, 1, 1, 1, 1, 1, 1, 1, 2

Offset: 1

Author

Reinhard Zumkeller, Aug 07 2002

Keywords

• nonn

Comments

a(n) = A062378(n) for n<90, but a(90)=3 <> A062378(90)=1.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A006530, A020639, A073752.

Differs from A062378 for the first time at n=90.

Programs

Mathematica

A073752[n_] := With[{f = FactorInteger[n][[All, 1]]}, GCD[n/f[[1]], n/f[[-1]]]];
a[n_] := A073752[A073752[n]];
Array[a, 100] (* Jean-François Alcover, Dec 03 2021 *)

Formula

a(n) = A073752(A073752(n)).

Extensions

Name edited by Antti Karttunen, Sep 23 2017