OFFSET
0,2
LINKS
Danny Rorabaugh, Table of n, a(n) for n = 0..10000
FORMULA
a(n-2) = Sum_{d|n, d<n} d^2*phi(n/d). - Vladeta Jovovic, Aug 27 2003
MATHEMATICA
Table[Sum[d^2*EulerPhi[(n + 2)/d], {d, Most@ Divisors[n + 2]}], {n, 0, 47}] (* Michael De Vlieger, Mar 20 2015 *)
PROG
(Sage) sum([d^2*euler_phi(int((n+2)/d)) for d in range(1, n+2) if (n+2)%d==0]) # Danny Rorabaugh, Mar 20 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved