A297086 a(n) = 1 if gcd(n, phi(n)) == 1 otherwise 0.

1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0

Offset

1

Comments

Characteristic function of A003277. - Iain Fox, Dec 25 2017

Links

Seiichi Manyama, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Totient Function

Formula

For even n > 2, a(n) = 0. - Iain Fox, Dec 25 2017

If n is in A013929 then a(n) = 0. - David A. Corneth, Dec 25 2017

a(n) = [gcd(n,phi(n)) = 1], where [ ] is the Iverson Bracket. - Wesley Ivan Hurt, Jan 20 2024

Example

gcd(5, phi(5)) = gcd(5, 4) = 1, so a(5) = 1.
gcd(6, phi(6)) = gcd(6, 2) = 2, so a(6) = 0.

Mathematica

Table[KroneckerDelta[GCD[n, EulerPhi[n]], 1], {n, 100}] (* Wesley Ivan Hurt, Jan 20 2024 *)

Prog

(PARI) {a(n) = gcd(n, eulerphi(n))==1}

Crossrefs

Cf. A000010 (phi), A003277, A013929, A061091.

Sequence in context: A080339 A294905 A353787 * A349920 A369253 A167752

Adjacent sequences: A297083 A297084 A297085 * A297087 A297088 A297089

Keyword

nonn,easy

Author

Seiichi Manyama, Dec 25 2017

Status

approved