OFFSET
1,1
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..100
PROG
(PARI) is(n) = n%2 && sumdiv(n, d, if(sigma(d, -1) < 2, 1, -1)) == 0;
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Sep 29 2022
STATUS
approved