A353805 a(n) = A051027(n) / gcd(A051027(n), A353802(n)), where A051027(n) = sigma(sigma(n)), and A353802(n) = Product_{p^e||n} sigma(sigma(p^e)).

1, 1, 1, 1, 1, 1, 1, 1, 1, 13, 1, 1, 1, 1, 5, 1, 1, 1, 1, 1, 3, 13, 1, 1, 1, 1, 1, 1, 1, 65, 1, 1, 31, 10, 31, 1, 1, 1, 5, 13, 1, 3, 1, 1, 1, 13, 1, 1, 1, 1, 5, 57, 1, 1, 65, 1, 31, 13, 1, 5, 1, 1, 1, 1, 7, 403, 1, 1, 3, 403, 1, 1, 1, 1, 1, 1, 3, 5, 1, 1, 1, 13, 1, 3, 70, 1, 5, 13, 1, 13, 31, 1, 85, 13, 5, 1, 1, 13

Offset

1,10

Comments

Denominator of fraction A353802(n) / A051027(n).

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Index entries for sequences related to sigma(n)

Formula

a(n) = A051027(n) / A353804(n).

Prog

(PARI)
A051027(n) = sigma(sigma(n));
A353805(n) = { my(f = factor(n)); (A051027(n) / gcd(A051027(n), prod(k=1, #f~, A051027(f[k, 1]^f[k, 2])))); };

Crossrefs

Cf. A000203, A051027, A353802, A353803, A353804, A353806 (numerators).

Positions of 1's is given by the union of A336547 and A353807.

Cf. also A353755, A353756.

Sequence in context: A367303 A357912 A251072 * A332018 A010227 A010228

Adjacent sequences: A353802 A353803 A353804 * A353806 A353807 A353808

Keyword

nonn,frac

Author

Antti Karttunen, May 08 2022

Status

approved