A324644 a(n) = gcd(sigma(n), A276086(n)), where A276086 is the primorial base exp-function, and sigma gives the sum of divisors of its argument.

1, 3, 2, 1, 6, 1, 2, 15, 1, 9, 6, 1, 2, 3, 6, 1, 18, 1, 10, 3, 2, 9, 6, 5, 1, 3, 10, 1, 30, 1, 2, 21, 6, 9, 6, 7, 2, 15, 14, 45, 42, 1, 2, 21, 6, 9, 6, 1, 1, 3, 6, 7, 18, 5, 2, 15, 10, 45, 30, 7, 2, 3, 2, 1, 42, 1, 2, 21, 6, 9, 18, 5, 2, 3, 2, 35, 6, 7, 10, 3, 1, 63, 42, 7, 2, 3, 30, 45, 90, 1, 14, 21, 2, 9, 6, 7, 98, 3, 6, 7, 6, 1, 2, 105, 6

Offset

1,2

Links

Antti Karttunen, Table of n, a(n) for n = 1..30030

Index entries for sequences related to primorial base.

Index entries for sequences related to sigma(n).

Formula

a(n) = gcd(A000203(n), A276086(n)).

Prog

(PARI)
A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A324644(n) = gcd(sigma(n), A276086(n));
(PARI) A324644(n) = { my(m=1, p=2, s=sigma(n)); while(n, m *= (p^min(n%p, valuation(s, p))); n = n\p; p = nextprime(1+p)); (m); }; \\ Antti Karttunen, Sep 17 2025

Crossrefs

Cf. A000203, A009194, A276086, A324198, A324534, A324645, A324646, A364286.

Cf. A088828 (positions of even terms), A176693 (of odd terms).

Cf. also A351458, A364286, A371082, A387163, A387165.

Sequence in context: A382347 A389710 A089145 * A364256 A361470 A134199

Adjacent sequences: A324641 A324642 A324643 * A324645 A324646 A324647

Keyword

nonn,base

Author

Antti Karttunen, Mar 11 2019

Status

approved