A388032 a(n) = gcd(A276086(sigma(n)), A276086(2*n)), where A276086 is the primorial base exp-function, and sigma is the sum of divisors function.

1, 3, 1, 5, 5, 25, 15, 75, 25, 125, 25, 625, 75, 625, 1, 7, 1, 35, 15, 35, 7, 35, 25, 7, 7, 175, 35, 13125, 7, 49, 21, 147, 35, 35, 35, 49, 105, 49, 875, 49, 175, 245, 525, 30625, 49, 49, 7, 343, 105, 1029, 1225, 5145, 175, 343, 1225, 343, 6125, 343, 49, 2401, 147, 343, 1715, 12005, 245, 60025, 735, 12005, 1715

Offset

1,2

Links

Antti Karttunen, Table of n, a(n) for n = 1..11550

Index entries for sequences related to primorial base.

Index entries for sequences related to sigma(n).

Formula

a(n) = gcd(A276086(2*n), A388031(n)).

Prog

(PARI)
A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A388032(n) = gcd(A276086(sigma(n)), A276086(2*n));

Crossrefs

Cf. A000203, A276086, A388031, A388034 [k such that a(k) = A276086(2k)].

Cf. also A388021, A388033.

Sequence in context: A146913 A146252 A181641 * A049266 A089028 A388225

Adjacent sequences: A388029 A388030 A388031 * A388033 A388034 A388035

Keyword

nonn

Author

Antti Karttunen, Sep 16 2025

Status

approved