OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
FORMULA
MATHEMATICA
a[n_] := n + DivisorSigma[1, n] - 2 * EulerPhi[n]; Array[a, 100] (* Amiram Eldar, Dec 04 2023 *)
PROG
(PARI)
A083254(n) = (2*eulerphi(n)-n);
(PARI) a(n) = {my(f = factor(n)); n + sigma(f) - 2*eulerphi(f); } \\ Amiram Eldar, Dec 04 2023
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Antti Karttunen, Feb 13 2019
STATUS
approved