A076233 Numbers k such that sigma(k)/k and sigma_3(k)/k are both integers.

1, 6, 120, 496, 672, 8128, 30240, 32760, 523776, 23569920, 33550336, 459818240, 1379454720, 1476304896, 8589869056, 31998395520, 51001180160, 66433720320, 137438691328, 153003540480, 403031236608, 30823866178560, 796928461056000, 6088728021160320, 14942123276641920

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..156

Prog

(PARI) isok(n) = !(sigma(n) % n) && !(sigma(n, 3) % n); \\ Michel Marcus, Dec 26 2013

Crossrefs

Cf. A000203, A001158, A007691, A046763, A055709, A076231, A076234.

Sequence in context: A227027 A001219 A224303 * A066581 A054776 A076231

Adjacent sequences: A076230 A076231 A076232 * A076234 A076235 A076236

Keyword

nonn

Author

Labos Elemer, Oct 04 2002

Extensions

a(19)-a(25) from Amiram Eldar, May 09 2024

Status

approved