A318459 a(n) = gcd(n, tau(n), phi(n)), where tau = A000005 and phi = A000010.

1, 1, 1, 1, 1, 2, 1, 4, 3, 2, 1, 2, 1, 2, 1, 1, 1, 6, 1, 2, 1, 2, 1, 8, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 8, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 8, 1, 2, 1, 4, 1, 2, 3, 1, 1, 2, 1, 2, 1, 2, 1, 12, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 12, 1, 2, 1, 8, 1, 6, 1, 2, 1, 2, 1, 4, 1, 2, 3, 1, 1, 2, 1, 8, 1

Offset: 1

Author

Antti Karttunen, Sep 07 2018, after Labos Elemer's A074389

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537

Crossrefs

Cf. A000005, A000010, A009191, A009195, A009213.

Cf. also A074389.

Programs

Mathematica

Table[GCD[n,DivisorSigma[0,n],EulerPhi[n]],{n,110}] (* Harvey P. Dale, Jul 30 2019 *)

PARI

A318459(n) = gcd([n, numdiv(n), eulerphi(n)]);

Formula

a(n) = gcd(n, A000005(n), A000010(n)).

a(n) = gcd(n,A009213(n)) = gcd(A000005(n),A009195(n)) = gcd(A000010(n),A009191(n)).