A367455 Numbers not divisible by 6 that are neither squarefree nor prime powers.

20, 28, 40, 44, 45, 50, 52, 56, 63, 68, 75, 76, 80, 88, 92, 98, 99, 100, 104, 112, 116, 117, 124, 135, 136, 140, 147, 148, 152, 153, 160, 164, 171, 172, 175, 176, 184, 188, 189, 196, 200, 207, 208, 212, 220, 224, 225, 232, 236, 242, 244, 245, 248, 250, 260, 261

Offset

1,1

Comments

A364997 is a proper subset.

The asymptotic density of this sequence is 1/6 - 1/(2*Pi^2). - Amiram Eldar, Jan 20 2024

Links

Michael De Vlieger, Table of n, a(n) for n = 1..10000

Formula

Intersection of A047253 and A126706.

Let p = A119288(k) and q = A053669(k) for k in A126706. Various definitions of this sequence:

{a(n)} = { k : Omega(k) > omega(k) > 1, p > q }.

{a(n)} = { k : Omega(k) > omega(k) > 1, k mod 6 != 0 }.

{a(n)} = { k = mx : x in A367018, rad(m) | x, m > 1. }.

Mathematica

Select[Range[261], And[Nor[SquareFreeQ[#], PrimePowerQ[#]], Mod[#, 6] != 0] &]

Crossrefs

Cf. A001221, A001222, A047253, A053669, A119288, A126706, A364997, A365710, A367018.

Sequence in context: A367632 A137428 A368089 * A350841 A361867 A309769

Adjacent sequences: A367452 A367453 A367454 * A367456 A367457 A367458

Keyword

nonn,easy

Author

Michael De Vlieger, Jan 15 2024

Status

approved