OFFSET
1,3
COMMENTS
a(n) is always >= 0.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Squarefree Part.
Eric Weisstein's World of Mathematics, Totient Function.
FORMULA
MATHEMATICA
f[n_] := Times @@ (First[#]^Mod[Last[#], 2] & /@ FactorInteger[n]) - EulerPhi[n]; Accumulate @ Array[f, 100] (* Amiram Eldar, Sep 06 2020 *)
PROG
(PARI) for(n=1, 100, print1(sum(i=1, n, core(i)-eulerphi(i)), ", "))
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Benoit Cloitre, May 08 2002
EXTENSIONS
Various sections edited by Petros Hadjicostas, May 11 2020
STATUS
approved