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A028499 6-hyperperfect numbers: n = 6*(sigma(n) - n - 1) + 1. 7
301, 16513, 60110701, 1977225901, 2733834545701, 232630479398401 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(7) > 10^17. - Max Alekseyev, Nov 25 2019

(7^k-6)*7^(k-1) is a term for all k in A191469. - Max Alekseyev, Nov 17 2019

336823287227717101 = 7^6*1340243*2136143 is also a term. - Giovanni Resta, Nov 18 2019

LINKS

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

Antal Bege, Kinga Fogarasi, Generalized perfect numbers, Acta Univ. Sapientiae, Math., 1 (2009), 73-82.

Judson S. McCranie, A Study of Hyperperfect Numbers, Journal of Integer Sequences, Vol. 3 (2000), Article 00.1.3.

Eric Weisstein's World of Mathematics, Hyperperfect Number

PROG

(PARI) isok(n) = 6*(sigma(n) - n - 1) + 1 == n; \\ Michel Marcus, Nov 18 2019

CROSSREFS

Cf. A000396, A007593, A028500, A028501, A028502, A034916, A220290.

Sequence in context: A300033 A178267 A296961 * A145123 A068258 A075407

Adjacent sequences:  A028496 A028497 A028498 * A028500 A028501 A028502

KEYWORD

hard,more,nonn

AUTHOR

Jud McCranie

EXTENSIONS

a(5) from Donovan Johnson, Nov 20 2012

a(6) from Donovan Johnson confirmed by Max Alekseyev, Nov 17 2019

STATUS

approved

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Last modified July 13 22:21 EDT 2020. Contains 335716 sequences. (Running on oeis4.)