A076231 Numbers n such that sigma(n)/n, sigma_3(n)/n and sigma_5(n)/n are integers.

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

Offset

1,2

Links

Table of n, a(n) for n=1..20.

Prog

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

Crossrefs

Intersection of A007691, A046763 and A055709.

Cf. A007691, A046763, A055709, A076233, A076234.

Sequence in context: A076233 A066581 A054776 * A076234 A066289 A351862

Adjacent sequences: A076228 A076229 A076230 * A076232 A076233 A076234

Keyword

nonn

Author

Labos Elemer, Oct 03 2002

Extensions

a(16)-a(20) from Donovan Johnson, May 08 2010

Status

approved