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

1333, 1909, 2469601, 893748277, 322685352001, 8992165119733, 42052982615431201, 1978419655654505210563957

Offset

1,1

Comments

Also includes 257829627945305630423565899317 and 63796332447481537808062775987165906562037. - Max Alekseyev, Jan 14 2026

Links

Table of n, a(n) for n=1..8.

Max A. Alekseyev, Computing bounded solutions to linear Diophantine equations with the sum of divisors, arXiv:2601.17832 [math.NT], 2026. See p. 9, Table 2.

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 and added by Max Alekseyev, Nov 21 2019

a(8) from Donovan Johnson confirmed and added by Max Alekseyev, Mar 07 2026

Status

approved