A379491 Multiperfect numbers k for which gcd(k,A003961(k))*gcd(sigma(k),A276086(k)) is equal to gcd(k,A276086(k))*gcd(sigma(k),A003961(k)), where A003961(n) is fully multiplicative with a(prime(i)) = prime(i+1), and A276086 is the primorial base exp-function.

1, 6, 28, 496, 8128, 30240, 32760, 2178540, 23569920, 33550336, 45532800, 142990848, 459818240, 1379454720, 8589869056, 43861478400, 51001180160, 66433720320, 137438691328, 153003540480, 403031236608, 704575228896, 181742883469056, 6088728021160320, 14942123276641920, 20158185857531904, 275502900594021408, 622286506811515392

Offset: 1

Author

Antti Karttunen, Jan 02 2025

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..993
• Index entries for sequences related to prime indices in the factorization of n.
• Index entries for sequences related to primorial base.
• Index entries for sequences related to sigma(n).

Crossrefs

Intersection of A007691 and A379486.

Cf. A000203, A003961, A276086, A322361, A324198, A324644, A342671, A379485, A379487, A379488, A379492 (complement in A007691).

Subsequences: A323653 (conjectured), A336702 (apart from any hypothetical odd terms > 1).

Programs

PARI

isA379491(n) = (!(sigma(n)%n) && A379485(n));