OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..55
PROG
(PARI) isok(n) = !(sigma(n) % n) && !(sigma(n, 3) % n) && !(sigma(n, 5) % n) && !(sigma(n, 7) % n); \\ Michel Marcus, Dec 26 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 04 2002
EXTENSIONS
a(13)-a(18) from Donovan Johnson, May 08 2010
a(19)-a(21) from Amiram Eldar, May 09 2024
STATUS
approved