OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16384
FORMULA
a(n) = n / A359594(n).
Sum_{k=1..n} a(k) ~ c * n^2, where c = (1/2) * Product_{p prime} (1 - p^(p-1)*(p-1)/(p^(2*p)-1)) = 0.4225104173... . - Amiram Eldar, Jan 11 2023
MATHEMATICA
f[p_, e_] := If[Divisible[e, p], 1, p^e]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Jan 09 2023 *)
PROG
(PARI) A359593(n) = { my(f = factor(n)); prod(k=1, #f~, f[k, 1]^(f[k, 2]*!!(f[k, 2]%f[k, 1]))); };
(Python)
from math import prod
from sympy import factorint
def A359593(n): return prod(p**e for p, e in factorint(n).items() if e%p) # Chai Wah Wu, Jan 10 2023
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Antti Karttunen, Jan 09 2023
STATUS
approved