A374042 Numbers k such that A276085(k) and A328768(k) are both multiples of 3, where A276085 is the primorial base log-function, and A328768 is the first primorial based variant of arithmetic derivative.

1, 5, 7, 8, 11, 13, 17, 19, 23, 25, 27, 29, 31, 35, 36, 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, 135, 136, 137, 139, 143, 145, 149, 151, 152, 155, 157, 161, 162, 163, 167, 169, 173, 175, 179

Offset: 1

Author

Antti Karttunen, Jun 26 2024

Keywords

• nonn

Comments

Numbers whose 3-adic valuation is not 1 and whose 2-adic and 3-adic valuations are equal modulo 3.

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

Links

• Antti Karttunen, Table of n, a(n) for n = 1..12000
• Index entries for sequences related to primorial numbers

Crossrefs

Intersection of A339746 and A373992.

Positions of multiples of 3 in A374031.

Cf. A276085, A328768, A374041 (characteristic function), A374044 (subsequence).

Programs

PARI

isA374042 = A374041;

Formula

{k | A007814(k) == A007949(n) (mod 3), A007949(k) != 1}.