cp's OEIS Frontend

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.

%I A379491 #8 Jan 03 2025 09:34:45
%S A379491 1,6,28,496,8128,30240,32760,2178540,23569920,33550336,45532800,
%T A379491 142990848,459818240,1379454720,8589869056,43861478400,51001180160,
%U A379491 66433720320,137438691328,153003540480,403031236608,704575228896,181742883469056,6088728021160320,14942123276641920,20158185857531904,275502900594021408,622286506811515392
%N 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.
%H A379491 Antti Karttunen, <a href="/A379491/b379491.txt">Table of n, a(n) for n = 1..993</a>
%H A379491 <a href="/index/Pri#prime_indices">Index entries for sequences related to prime indices in the factorization of n</a>.
%H A379491 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>.
%H A379491 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>.
%o A379491 (PARI) isA379491(n) = (!(sigma(n)%n) && A379485(n));
%Y A379491 Intersection of A007691 and A379486.
%Y A379491 Cf. A000203, A003961, A276086, A322361, A324198, A324644, A342671, A379485, A379487, A379488, A379492 (complement in A007691).
%Y A379491 Subsequences: A323653 (conjectured), A336702 (apart from any hypothetical odd terms > 1).
%K A379491 nonn
%O A379491 1,2
%A A379491 _Antti Karttunen_, Jan 02 2025