A074465 a(n) = gcd(n^2, sigma(n^2), phi(n^2)).

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 39, 1, 1, 21, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 7, 1, 1, 1, 1, 1, 1, 7, 39, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 7, 11, 1, 1, 1, 1

Offset: 1

Author

Labos Elemer, Aug 23 2002

Keywords

• nonn

Comments

a(n) is odd because sigma(n^2) is odd;.

Examples

			For n=14: gcd(196,399,84) = 7 = a(14).
		

Links

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

Crossrefs

Cf. A000203, A002618, A065764, A074389, A074466.

Programs

Mathematica

Table[Apply[GCD, {w^2, DivisorSigma[1, w^2], EulerPhi[w^2]}], {w, 1, 128}]

PARI

A074465(n) = gcd([n^2, sigma(n^2), eulerphi(n^2)]); \\ Antti Karttunen, Sep 07 2018

Formula

a(n) = A074389(n^2).