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A055708

Numbers n such that n - 1 | sigma(n).

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 A368063 A364140` `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`

Last modified August 5 23:35 EDT 2024. Contains 374957 sequences. (Running on oeis4.)