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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.
5
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
OFFSET
1,1
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); };
A388033(n) = gcd(A276086(sigma(n)), A276086(3*n));
CROSSREFS
Cf. A000203, A276086, A388031, A388036 [k such that a(k) = A276086(3k)].
Cf. also A388021, A388032.
Sequence in context: A167595 A328600 A378961 * A179382 A161169 A239738
KEYWORD
nonn
AUTHOR
Antti Karttunen, Sep 16 2025
STATUS
approved