A028501 18-hyperperfect numbers: n = 18*(sigma(n)-n-1) + 1.

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

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