OFFSET
1,1
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
PROG
(PARI) isok(m) = isprimepower(m) && isprime(sigma(m^2, 4)/sigma(m^2, 2)); \\ Michel Marcus, Apr 06 2020
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Dec 06 2001
STATUS
approved