OFFSET
1,1
COMMENTS
a(7) > 10^17. - Max Alekseyev, Nov 25 2019
(7^k-6)*7^(k-1) is a term for all k in A191469. - Max Alekseyev, Nov 17 2019
336823287227717101 = 7^6*1340243*2136143 is also a term. - Giovanni Resta, Nov 18 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) = 6*(sigma(n) - n - 1) + 1 == n; \\ Michel Marcus, Nov 18 2019
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
EXTENSIONS
a(5) from Donovan Johnson, Nov 20 2012
a(6) from Donovan Johnson confirmed by Max Alekseyev, Nov 17 2019
STATUS
approved