A073464 a(n) = phi(n) mod PrimePi(n).

0, 0, 0, 1, 2, 2, 0, 2, 0, 0, 4, 0, 0, 2, 2, 2, 6, 2, 0, 4, 2, 4, 8, 2, 3, 0, 3, 8, 8, 8, 5, 9, 5, 2, 1, 0, 6, 0, 4, 1, 12, 0, 6, 10, 8, 1, 1, 12, 5, 2, 9, 4, 2, 8, 8, 4, 12, 7, 16, 6, 12, 0, 14, 12, 2, 9, 13, 6, 5, 10, 4, 9, 15, 19, 15, 18, 3, 12, 10, 10, 18, 13, 1, 18, 19, 10, 17, 16, 0, 0, 20, 12

Offset: 2

Author

Labos Elemer, Aug 02 2002

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 2..10000

Crossrefs

Cf. A000010, A000720.

Cf. A037228, A037171.

Cf. A073453, A073454, A073455, A073456, A073457, A072530, A072531, A073461, A073461.

Programs

Magma

[EulerPhi(n) mod #PrimesUpTo(n): n in [2..100]]; // Vincenzo Librandi, Dec 11 2018

Mathematica

a(n)=Table[Mod[EulerPhi[w], PrimePi[w]], {w, 2, 1000}]

PARI

a(n) = eulerphi(n) % primepi(n); \\ Michel Marcus, Dec 11 2018

Formula

a(n) = A000010(n) mod A000720(n).