OFFSET
1,2
COMMENTS
If n is prime, then a(n) = 4n.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..10000
FORMULA
From Amiram Eldar, Dec 04 2023: (Start)
MATHEMATICA
Table[DivisorSigma[1, n]^2-EulerPhi[n]^2, {n, 50}] (* Harvey P. Dale, Nov 08 2013 *)
PROG
(PARI) A077101(n) = (sigma(n)^2 - eulerphi(n)^2); \\ Antti Karttunen, May 26 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Labos Elemer, Nov 06 2002
EXTENSIONS
Edited by Dean Hickerson, Nov 07 2002
STATUS
approved