A193454 Sum of odd divisors of phi(n).

1, 1, 1, 1, 1, 1, 4, 1, 4, 1, 6, 1, 4, 4, 1, 1, 1, 4, 13, 1, 4, 6, 12, 1, 6, 4, 13, 4, 8, 1, 24, 1, 6, 1, 4, 4, 13, 13, 4, 1, 6, 4, 32, 6, 4, 12, 24, 1, 32, 6, 1, 4, 14, 13, 6, 4, 13, 8, 30, 1, 24, 24, 13, 1, 4, 6, 48, 1, 12, 4, 48, 4, 13, 13, 6, 13, 24, 4

Offset: 1

Author

Michel Lagneau, Jul 26 2011

Keywords

• nonn

Comments

Phi(n): A000010 is the Euler totient function. This sequence equals A193254(n) for n < 63.

Examples

			a(63) = 13 because phi(63) = 36, and the sum of the 3 odd divisors {1, 3, 9} is 13.
		

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000010, A193254.

Programs

Mathematica

Table[Total[Select[Divisors[EulerPhi[n]], OddQ[ # ]&]], {n, 58}]

PARI

a(n) = sumdiv(eulerphi(n), d, (d%2)*d); \\ Michel Marcus, Jan 14 2014

Formula

a(n) = A000593(A000010(n)). - Michel Marcus, Jan 14 2014