OFFSET
1,4
FORMULA
a(n) = Sum_{p|n prime} p^(n/p - 1).
If p is prime, a(p) = 1.
MAPLE
A373458 := proc(n)
local a, d ;
a := 0 ;
for d in numtheory[divisors](n) do
if isprime(d) then
a := a+d^(n/d-1) ;
end if;
end do:
a ;
end proc:
seq(A373458(n), n=1..20) ; # R. J. Mathar, Jun 07 2024
PROG
(PARI) a(n) = sumdiv(n, d, isprime(d)*d^(n/d-1));
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Seiichi Manyama, Jun 06 2024
STATUS
approved