A261872 a(n) = phi(n) mod 5, where phi is the Euler totient function.

1, 1, 2, 2, 4, 2, 1, 4, 1, 4, 0, 4, 2, 1, 3, 3, 1, 1, 3, 3, 2, 0, 2, 3, 0, 2, 3, 2, 3, 3, 0, 1, 0, 1, 4, 2, 1, 3, 4, 1, 0, 2, 2, 0, 4, 2, 1, 1, 2, 0, 2, 4, 2, 3, 0, 4, 1, 3, 3, 1, 0, 0, 1, 2, 3, 0, 1, 2, 4, 4, 0, 4, 2, 1, 0, 1, 0, 4, 3, 2, 4, 0, 2, 4, 4, 2, 1, 0, 3, 4, 2, 4, 0, 1, 2, 2, 1, 2, 0, 0, 0, 2, 2, 3, 3

Offset: 1

Author

Vincenzo Librandi, Sep 04 2015

Keywords

• nonn
• easy

Links

• Antti Karttunen, Table of n, a(n) for n = 1..16384

Crossrefs

Cf. A000010, A010874, A074942, A084300.

Programs

Magma

[EulerPhi(n) mod 5: n in [1..110]];

Mathematica

Table[Mod[EulerPhi[n], 5], {n, 110}]

PARI

a(n) = eulerphi(n) % 5; \\ Michel Marcus, Sep 05 2015

Formula

a(n) = A000010(n) mod 5 = A010874(A000010(n)).

Extensions

More terms from Antti Karttunen, Dec 04 2017