A080647 Sum of prime factors of phi(n).

2, 2, 2, 2, 5, 2, 5, 2, 7, 2, 5, 5, 2, 2, 2, 5, 5, 2, 5, 7, 13, 2, 7, 5, 5, 5, 9, 2, 10, 2, 7, 2, 5, 5, 5, 5, 5, 2, 7, 5, 12, 7, 5, 13, 25, 2, 12, 7, 2, 5, 15, 5, 7, 5, 5, 9, 31, 2, 10, 10, 5, 2, 5, 7, 16, 2, 13, 5, 14, 5, 5, 5, 7, 5, 10, 5, 18, 2, 5, 7, 43, 5, 2, 12, 9, 7, 13, 5, 5, 13, 10, 25, 5, 2, 5

Offset

3,1

Links

Indranil Ghosh, Table of n, a(n) for n = 3..10000

Formula

a(n) = A008472(A000010(n)). - Indranil Ghosh, Jan 18 2017

Example

For n = 11, phi(11) = 10 which has prime factors 2 and 5. So, 2+5 = 7 and a(11) = 7. - Indranil Ghosh, Jan 18 2017

Mathematica

Table[Apply[Plus, Transpose[FactorInteger[EulerPhi[n]]][[1]]], {n, 3, 100}]
Table[Total[FactorInteger[EulerPhi[n]][[All, 1]]], {n, 3, 100}] (* Harvey P. Dale, May 30 2020 *)

Crossrefs

Cf. A000010, A008472.

Sequence in context: A221491 A224254 A107604 * A324516 A181058 A301452

Adjacent sequences: A080644 A080645 A080646 * A080648 A080649 A080650

Keyword

nonn

Author

Joseph L. Pe, Feb 28 2003

Status

approved