A374044 Non-multiples of 3 whose 2-adic valuation is a multiple of 3.

1, 5, 7, 8, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 40, 41, 43, 47, 49, 53, 55, 56, 59, 61, 64, 65, 67, 71, 73, 77, 79, 83, 85, 88, 89, 91, 95, 97, 101, 103, 104, 107, 109, 113, 115, 119, 121, 125, 127, 131, 133, 136, 137, 139, 143, 145, 149, 151, 152, 155, 157, 161, 163, 167, 169, 173, 175, 179, 181, 184, 185, 187

Offset: 1

Author

Antti Karttunen, Jun 27 2024

Keywords

• nonn
• easy

Comments

A multiplicative semigroup: if m and n are in the sequence, then so is m*n.

The asymptotic density of this sequence is 8/21. - Amiram Eldar, Jun 28 2024

Links

• Antti Karttunen, Table of n, a(n) for n = 1..12000

Crossrefs

Cf. A007814, A007949, A374043 (characteristic function).

Intersection of A001651 and A191257.

Subsequence of A339746, of A373992, and of A374042.

Programs

Mathematica

Select[Range[200], !Divisible[#, 3] && Divisible[IntegerExponent[#, 2], 3] &] (* Amiram Eldar, Jun 28 2024 *)

PARI

isA374044 = A374043;

Formula

{k | A007814(k) == 0 (mod 3), A007949(k) = 0}.