A388278 a(n) = gcd(sigma(n), A276086(sigma(n))), where A276086 is the primorial base exp-function, and sigma is the sum of divisors function.

1, 3, 1, 1, 1, 1, 1, 15, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 5, 7, 1, 1, 1, 1, 1, 7, 5, 7, 1, 1, 1, 21, 1, 1, 1, 7, 1, 1, 7, 1, 7, 1, 1, 7, 1, 1, 1, 1, 3, 3, 1, 49, 1, 1, 1, 1, 5, 1, 1, 7, 1, 1, 1, 1, 7, 1, 1, 7, 1, 1, 1, 15, 1, 1, 1, 35, 1, 7, 5, 1, 1, 7, 7, 1, 1, 1, 1, 1, 1, 1, 7, 7, 1, 1, 1, 7, 49, 3, 1, 1, 1, 1, 1, 1, 1

Offset

1,2

Links

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

Index entries for sequences related to primorial base.

Index entries for sequences related to sigma(n).

Formula

a(n) = gcd(A000203(n), A388031(n)).

a(n) = A324198(A000203(n)).

Prog

(PARI)
A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A388278(n) = gcd(sigma(n), A276086(sigma(n)));

Crossrefs

Cf. A000203, A276086, A324198, A388031.

Sequence in context: A135939 A061653 A326697 * A366168 A016565 A051714

Adjacent sequences: A388275 A388276 A388277 * A388279 A388280 A388281

Keyword

nonn

Author

Antti Karttunen, Sep 16 2025

Status

approved