OFFSET
1,2
COMMENTS
First negative term occurs as a(1440) = -18.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..16560
Antti Karttunen, Data supplement: n, a(n) computed for n = 1..65537
FORMULA
MATHEMATICA
f[p_, e_] := (p^(e+1) - 1)/(p-1); a[1] = 1; a[n_] := Module[{fct = FactorInteger[n]}, n * (Times @@ (1 + 1/fct[[;; , 1]]) + 1) - Times @@ f @@@ fct]; Array[a, 100] (* Amiram Eldar, Dec 08 2023 *)
PROG
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Antti Karttunen, May 28 2021
STATUS
approved