A336397 Numbers k such that both k and A122111(k) [its conjugated prime factorization] are Ore's Harmonic numbers (A001599).

1, 6, 753480, 429520946400

Offset: 1

Author

Antti Karttunen, Jul 20 2020

Keywords

• nonn
• hard
• more

Comments

The initial four terms were found from the b-file of 937 terms provided in A001599.

There also at least these additional terms present: 439151400324000, 889013810412000, 106713790278732000, that were found from the file of conjectured initial 10000 terms of A001599 provided by David A. Corneth under that entry. However, there might be further terms in the range between.

Note that A122111(889013810412000) = 106713790278732000, and vice versa, which proves that the intersection of A001599 and A088902 (equal to the intersection of A088902 with A336317) is not equal to this sequence, but just a proper subsequence.

Crossrefs

Intersection of A001599 and A336317.

Cf. A088902, A122111.

Programs

PARI

isA001599(n) = !((sigma(n,0)*n)%sigma(n,1));
isA336397(n) = (isA001599(n) && isA001599(A122111(n)));
\\ Or alternatively, by using standalone program given in A336317:
isA336397(n) = (isA001599(n) && isA336317(n));