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A028501 18-hyperperfect numbers: n = 18*(sigma(n)-n-1) + 1. 4
1333, 1909, 2469601, 893748277, 322685352001, 8992165119733, 42052982615431201 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
1978419655654505210563957 are also terms. - Donovan Johnson, Nov 20 2012
a(8) > 10^17. - Max Alekseyev, Nov 17 2019
LINKS
Table of n, a(n) for n=1..7.
Judson S. McCranie, A Study of Hyperperfect Numbers, Journal of Integer Sequences, Vol. 3 (2000), Article 00.1.3.
CROSSREFS
Cf. A000396, A007593, A220290, A028499, A028500, A028502, A034916.
Sequence in context: A035862 A003907 A043613 * A183646 A250902 A250946
Adjacent sequences: A028498 A028499 A028500 * A028502 A028503 A028504
KEYWORD
hard,more,nonn
AUTHOR
Jud McCranie
EXTENSIONS
a(5) from Donovan Johnson, Nov 03 2011
a(6)-a(7) from Donovan Johnson confirmed by Max Alekseyev, Nov 21 2019
STATUS
approved

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Last modified May 23 11:57 EDT 2024. Contains 372763 sequences. (Running on oeis4.)