OFFSET
1,3
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
FORMULA
Sum_{k=1..n} a(k) ~ c * n^2 / 2, where c = A065487 - A013661 + 1 = 0.586357... . - Amiram Eldar, Dec 08 2023
MATHEMATICA
f[p_, e_] := (p^(e + 1) - 1)/(p - 1); fc[p_, e_] := f[p, e] - 1; a[1] = 1; a[n_] := n - Times @@ f @@@ (fct = FactorInteger[n]) + Times @@ fc @@@ fct; Array[a, 100] (* Amiram Eldar, Dec 08 2023 *)
PROG
CROSSREFS
KEYWORD
sign
AUTHOR
Antti Karttunen, Jul 27 2020
STATUS
approved