A076234 Numbers n such that sigma(n)/n, sigma_3(n)/n, sigma_5(n)/n and sigma_7(n)/n are integers.

1, 6, 120, 672, 30240, 32760, 33550336, 459818240, 1379454720, 8589869056, 31998395520, 51001180160, 137438691328, 153003540480, 30823866178560, 796928461056000, 6088728021160320, 212517062615531520

Offset

1,2

Links

Table of n, a(n) for n=1..18.

Prog

(PARI) isok(n) = !(sigma(n) % n) && !(sigma(n, 3) % n) && !(sigma(n, 5) % n) && !(sigma(n, 7) % n); \\ Michel Marcus, Dec 26 2013

Crossrefs

Cf. A007691, A046763, A055709, A076231, A076233.

Cf. A066289 (n divides sigma_k(n) for all odd k).

Sequence in context: A066581 A054776 A076231 * A066289 A351862 A170917

Adjacent sequences: A076231 A076232 A076233 * A076235 A076236 A076237

Keyword

nonn

Author

Labos Elemer, Oct 04 2002

Extensions

a(13)-a(18) from Donovan Johnson, May 08 2010

Status

approved