A076480 a(n) = n + mu(rad(n)), where mu is the Moebius function (A008683) and rad is the squarefree kernel (A007947).

2, 1, 2, 3, 4, 7, 6, 7, 8, 11, 10, 13, 12, 15, 16, 15, 16, 19, 18, 21, 22, 23, 22, 25, 24, 27, 26, 29, 28, 29, 30, 31, 34, 35, 36, 37, 36, 39, 40, 41, 40, 41, 42, 45, 46, 47, 46, 49, 48, 51, 52, 53, 52, 55, 56, 57, 58, 59, 58, 59, 60, 63, 64, 63, 66, 65, 66, 69, 70, 69, 70, 73

Offset: 1

Author

Reinhard Zumkeller, Oct 14 2002

Keywords

• nonn
• easy

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A007947, A008683, A076479.

Programs

Mathematica

a[n_] := n + (-1)^PrimeNu[n]; Array[a, 100] (* Amiram Eldar, Apr 10 2025 *)

PARI

a(n)=n+(-1)^omega(n) \\ Charles R Greathouse IV, Aug 08 2013

Formula

a(n) = n + A076479(n) = n + A008683(A007947(n)).