A368642 a(n) = Sum_{k=1..n} mu(k)^2 * ceiling(n/k), where mu is the Möbius function (A008683).

1, 3, 6, 8, 11, 14, 19, 21, 23, 26, 31, 33, 38, 41, 46, 50, 53, 55, 60, 62, 67, 72, 77, 79, 83, 86, 90, 92, 97, 100, 109, 111, 114, 119, 124, 128, 133, 136, 141, 145, 150, 153, 162, 164, 168, 173, 178, 180, 184, 186, 191, 195, 200, 202, 207, 211, 216, 221, 226, 228

Offset: 1

Author

Wesley Ivan Hurt, Jan 01 2024

Keywords

• nonn
• easy

Crossrefs

Cf. A008683 (mu), A008966, A013928, A034444, A064608.

Programs

Mathematica

Table[Sum[MoebiusMu[k]^2*Ceiling[n/k], {k, n}], {n, 100}]

Formula

a(n) = A013928(n) + A008966(n) + A064608(n) - A034444(n).