A174030 Partial sums of A007694.

1, 3, 7, 13, 21, 33, 49, 67, 91, 123, 159, 207, 261, 325, 397, 493, 601, 729, 873, 1035, 1227, 1443, 1699, 1987, 2311, 2695, 3127, 3613, 4125, 4701, 5349, 6117, 6981, 7953, 8977, 10129, 11425, 12883, 14419, 16147, 18091, 20139, 22443, 25035, 27951, 31023

Offset: 1

Author

Jonathan Vos Post, Mar 06 2010

Keywords

• nonn

Comments

Partial sums of numbers k such that phi(k) divides k.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A000010, A007694, A259823.

Programs

Mathematica

Accumulate[Select[Range[5000], Divisible[#, EulerPhi[#]] &]] (* Amiram Eldar, Nov 05 2024 *)

Formula

a(n) = Sum_{i=1..n} A007694(i).

a(n) = 2*A259823(n-1) + 1. - Amiram Eldar, Nov 05 2024