A353755 a(n) = A062401(n) / gcd(A062401(n), A353752(n)), where A062401(n) = phi(sigma(n)), and A353752(n) = Product_{p^e||n} phi(sigma(p^e)).

1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 2, 3, 2, 1, 1, 1, 2, 3, 1, 2, 1, 1, 1, 3, 1, 1, 1, 1, 2, 7, 1, 1, 3, 1, 2, 3, 1, 2, 1, 1, 1, 1, 2, 3, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 3, 1, 2, 3, 1, 2, 3, 1, 3, 2, 1, 2, 3, 2, 1, 1, 3, 1, 1, 1, 3, 1, 1, 4

Offset: 1

Author

Antti Karttunen, May 08 2022

Keywords

• nonn
• frac

Comments

Numerator of fraction A062401(n) / A353752(n).

Links

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

Crossrefs

Cf. A000010, A000203, A062401, A353752, A353753, A353754, A353756 (denominators).

Cf. A336547 (positions of 1's), A336548 (positions of terms > 1).

Cf. also A353805.

Programs

PARI

A062401(n) = eulerphi(sigma(n));
A353755(n) = { my(f = factor(n)); (A062401(n) / gcd(A062401(n), prod(k=1, #f~, A062401(f[k, 1]^f[k, 2])))); };

Formula

a(n) = A062401(n) / A353754(n) = A062401(n) / gcd(A062401(n), A353752(n)).