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A028501
18-hyperperfect numbers: n = 18*(sigma(n)-n-1) + 1.
4
1333, 1909, 2469601, 893748277, 322685352001, 8992165119733, 42052982615431201
OFFSET
1,1
COMMENTS
1978419655654505210563957 are also terms. - Donovan Johnson, Nov 20 2012
a(8) > 10^17. - Max Alekseyev, Nov 17 2019
LINKS
Judson S. McCranie, A Study of Hyperperfect Numbers, Journal of Integer Sequences, Vol. 3 (2000), Article 00.1.3.
KEYWORD
hard,more,nonn
AUTHOR
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