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A028500
12-hyperperfect numbers: n = 12*(sigma(n) - n - 1) + 1.
5
697, 2041, 1570153, 62722153, 10604156641, 13544168521, 1792155938521
OFFSET
1,1
COMMENTS
7056410014866537089009269921 is also a term. - Donovan Johnson, Nov 20 2012
Also terms: 13^7*815787979*11621986347871 and 13^23*542800770374370512771595349. - Giovanni Resta, Nov 18 2019
a(8) >= 10^17. - Max Alekseyev, Nov 22 2019
LINKS
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) = 12*(sigma(n) - n - 1) + 1 == n; \\ Michel Marcus, Nov 18 2019
KEYWORD
hard,more,nonn
AUTHOR
EXTENSIONS
a(7) from Donovan Johnson, Nov 20 2012
STATUS
approved