OFFSET
1,3
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
N. J. A. Sloane, Transforms.
FORMULA
Multiplicative with a(p^e) = 0 if e is even, and p^((e+1)/2) - p^((e-1)/2) if e is odd. - Amiram Eldar, Aug 19 2021
Sum_{k=1..n} a(k) ~ c * n^2, where c = 18*zeta(3)/Pi^4 = 0.222125... . - Amiram Eldar, Nov 18 2022
MATHEMATICA
f[p_, e_] := If[EvenQ[e], 0, p^((e + 1)/2) - p^((e - 1)/2)]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Aug 19 2021 *)
PROG
(PARI) a(n) = sumdiv(n, d, moebius(n/d)*d/core(d, 1)[2]); \\ Michel Marcus, Aug 18 2021
CROSSREFS
KEYWORD
nonn,mult,easy
AUTHOR
N. J. A. Sloane, Aug 18 2021
STATUS
approved