A388033 - OEIS

A388033

a(n) = gcd(A276086(sigma(n)), A276086(3*n)), where A276086 is the primorial base exp-function, and sigma is the sum of divisors function.

2, 1, 3, 5, 5, 25, 15, 25, 50, 1, 1, 5, 15, 25, 25, 7, 125, 35, 375, 7, 21, 35, 5, 49, 14, 175, 105, 4375, 7, 49, 21, 49, 35, 175, 175, 343, 105, 49, 13125, 343, 7, 1715, 105, 1225, 1225, 1225, 875, 2401, 26250, 343, 49, 1715, 35, 2401, 1225, 2401, 18375, 343, 49, 16807, 147, 1715, 5145, 12005, 1225, 300125, 735

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OFFSET

1,1

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(3*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); };