A348028 Greatest common divisor of A003415 (arithmetic derivative) and sigma, the sum of divisors function.

1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 4, 1, 3, 8, 1, 1, 3, 1, 6, 2, 1, 1, 4, 1, 3, 1, 8, 1, 1, 1, 1, 2, 1, 12, 1, 1, 3, 8, 2, 1, 1, 1, 12, 39, 1, 1, 4, 1, 3, 4, 14, 1, 3, 8, 4, 2, 1, 1, 4, 1, 3, 1, 1, 6, 1, 1, 18, 2, 1, 1, 39, 1, 3, 1, 20, 6, 1, 1, 2, 1, 1, 1, 4, 2, 3, 8, 20, 1, 3, 4, 24, 2, 1, 24, 4, 1, 1, 3, 7, 1, 1, 1, 2, 1

Offset: 1

Author

Antti Karttunen, Sep 25 2021

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537
• Index entries for sequences related to sigma(n)

Crossrefs

Cf. A000203, A003415.

Cf. also A342413, A342458, A343226.

Programs

PARI

A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A348028(n) = gcd(sigma(n), A003415(n));

Formula

a(n) = gcd(A000203(n), A003415(n)).