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A074465
a(n) = gcd(n^2, sigma(n^2), phi(n^2)).
3
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
1,14
COMMENTS
a(n) is odd because sigma(n^2) is odd;.
LINKS
FORMULA
a(n) = A074389(n^2).
EXAMPLE
For n=14: gcd(196,399,84) = 7 = a(14).
MATHEMATICA
Table[Apply[GCD, {w^2, DivisorSigma[1, w^2], EulerPhi[w^2]}], {w, 1, 128}]
PROG
(PARI) A074465(n) = gcd([n^2, sigma(n^2), eulerphi(n^2)]); \\ Antti Karttunen, Sep 07 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Aug 23 2002
STATUS
approved