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A076234 Numbers n such that sigma(n)/n, sigma_3(n)/n, sigma_5(n)/n and sigma_7(n)/n are integers. 3
1, 6, 120, 672, 30240, 32760, 33550336, 459818240, 1379454720, 8589869056, 31998395520, 51001180160, 137438691328, 153003540480, 30823866178560, 796928461056000, 6088728021160320, 212517062615531520 (list; graph; refs; listen; history; text; internal format)
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 A170917 A115678

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

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Last modified June 24 00:21 EDT 2021. Contains 345403 sequences. (Running on oeis4.)