OFFSET
1,6
LINKS
FORMULA
a(n) = Sum_{p over distinct primes dividing sigma(n)} [p|n], where [ ] is the Iverson bracket, giving in this case 1 only if p divides n, and 0 otherwise.
PROG
(PARI) A336388(n) = if(1==n, 0, #select(p -> !(n%p), factor(sigma(n))[, 1]));
CROSSREFS
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jul 25 2020
STATUS
approved