OFFSET
1,6
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
FORMULA
Additive with a(p^e) = e if e is odd, and e-1 if e is even.
From Amiram Eldar, Sep 29 2023:
EXAMPLE
12 has 4 bi-unitary divisors, 1, 3, 4 and 12. Two of these divisors, 3 and 4 = 2^2 are prime powers. Therefore a(12) = 2.
MATHEMATICA
f[p_, e_] := If[OddQ[e], e, e - 1]; a[1] = 0; a[n_] := Plus @@ f @@@ FactorInteger[n]; Array[a, 100]
PROG
(PARI) a(n) = vecsum(apply(x -> if(x%2, x, x-1), factor(n)[, 2])); \\ Amiram Eldar, Sep 29 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Amiram Eldar, Nov 15 2021
STATUS
approved