A179179 a(n) = phi(n) - omega(n) = A000010(n) - A001221(n).

1, 0, 1, 1, 3, 0, 5, 3, 5, 2, 9, 2, 11, 4, 6, 7, 15, 4, 17, 6, 10, 8, 21, 6, 19, 10, 17, 10, 27, 5, 29, 15, 18, 14, 22, 10, 35, 16, 22, 14, 39, 9, 41, 18, 22, 20, 45, 14, 41, 18, 30, 22, 51, 16, 38, 22, 34, 26, 57, 13, 59, 28, 34, 31, 46, 17, 65, 30, 42, 21, 69, 22, 71, 34, 38, 34, 58

Offset: 1

Author

Peter Luschny, Jun 30 2010

Keywords

• nonn

Comments

a(n) is the number of positive integers which are coprime to n minus the number of distinct primes dividing n.

Examples

			a(7) = phi(7) - omega(7) = card({1,2,3,4,5,6}) - card({7}) = 6 - 1 = 5
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..10000
• Peter Luschny, Blog on OEIS, Euler's totient function

Crossrefs

Cf. A000010, A001221, A057859.

Programs

Maple

with(numtheory): a := n -> phi(n) - nops(factorset(n));

Mathematica

Table[EulerPhi[n] - PrimeNu[n], {n,1,50}] (* G. C. Greubel, Apr 23 2017 *)

Formula

a(n) = phi(n) - omega(n), by definition.