OFFSET
1,2
COMMENTS
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
László Tóth, On certain arithmetic functions involving exponential divisors, II, Annales Univ. Sci. Budapest., Sect. Comp., Vol. 27 (2007), pp. 155-166, arXiv preprint, arXiv:0708.3557 [math.NT], 2007-2009.
FORMULA
Multiplicative with a(p^e) = p^rad(e), where rad(k) is the largest squarefree number dividing k (A007947).
Sum_{n<=x} a(n) = (1/2) * c * x^2, where c = Product_{p prime} Sum{k>=4} (p^rad(k) - p^(1+rad(k-1)))/p^(2*k) = 0.9646498658... (Tóth, 2007).
MATHEMATICA
rad[n_] := Times @@ (First@# & /@ FactorInteger[n]); f[p_, e_] := p^rad[e]; a[1]=1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100]
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
Amiram Eldar, Nov 08 2020
STATUS
approved