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A055708 Numbers n such that n - 1 | sigma(n). 4
2, 3, 10, 136, 32896, 2147516416 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(7) > 10^13. - Giovanni Resta, Jul 13 2015

LINKS

Table of n, a(n) for n=1..6.

MATHEMATICA

Do[ If[ Mod[ DivisorSigma[1, n], n - 1] == 0, Print[n] ], {n, 2, 10^8} ]

PROG

(PARI) is(n)=sigma(n)%(n-1)==0 \\ Anders Hellström, Aug 15 2015

CROSSREFS

Cf. A000203, A045768, A056006.

Sequence in context: A076927 A064647 A119810 * A162647 A132536 A322067

Adjacent sequences:  A055705 A055706 A055707 * A055709 A055710 A055711

KEYWORD

nonn,more

AUTHOR

Robert G. Wilson v, Dec 04 2000

EXTENSIONS

a(6) from Donovan Johnson, Nov 15 2009

STATUS

approved

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Last modified December 10 14:27 EST 2019. Contains 329896 sequences. (Running on oeis4.)