A368998 Numbers k such that A003415(k) and A276085(k) are both even, where A003415 is the arithmetic derivative and A276085 is the primorial base log-function; Numbers k for which A342001(k) is even.

1, 4, 9, 12, 15, 16, 20, 21, 25, 28, 33, 35, 36, 39, 44, 48, 49, 51, 52, 55, 57, 60, 64, 65, 68, 69, 76, 77, 80, 81, 84, 85, 87, 91, 92, 93, 95, 100, 108, 111, 112, 115, 116, 119, 121, 123, 124, 129, 132, 133, 135, 140, 141, 143, 144, 145, 148, 155, 156, 159, 161, 164, 169, 172, 176, 177, 180, 183, 185, 187, 188, 189

Offset

1,2

Comments

From Antti Karttunen, Jun 03 2024: (Start)

Also numbers k for which A373145(k) is even, or in other words, numbers k such that A003415(k) and A276085(k) are both even.

Because both A003159 and A235992 are multiplicative semigroups, this is also: if m and n are in the sequence then so is m*n.

(End)

Links

Antti Karttunen, Table of n, a(n) for n = 1..20000

Prog

(PARI) isA368998 = A368997;

Crossrefs

Cf. A000290, A003415, A276085, A368995 (subsequence), A368997 (characteristic function), A368999 (complement).

Positions of even terms in A342001 and in A373145.

Intersection of A003159 and A235992.

Disjoint union of A345452 and 2*A358776.

Sequence in context: A179395 A175251 A386316 * A388970 A386318 A287367

Adjacent sequences: A368995 A368996 A368997 * A368999 A369000 A369001

Keyword

nonn

Author

Antti Karttunen, Jan 14 2024

Extensions

Alternative definition added as a new primary definition by Antti Karttunen, Jun 04 2024

Status

approved