OFFSET
1,2
COMMENTS
Partial sums of numbers k such that phi(k) divides k.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = Sum_{i=1..n} A007694(i).
a(n) = 2*A259823(n-1) + 1. - Amiram Eldar, Nov 05 2024
MATHEMATICA
Accumulate[Select[Range[5000], Divisible[#, EulerPhi[#]] &]] (* Amiram Eldar, Nov 05 2024 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan Vos Post, Mar 06 2010
STATUS
approved