cp's OEIS Frontend

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.

%I A368998 #20 Jun 04 2024 10:52:20
%S A368998 1,4,9,12,15,16,20,21,25,28,33,35,36,39,44,48,49,51,52,55,57,60,64,65,
%T A368998 68,69,76,77,80,81,84,85,87,91,92,93,95,100,108,111,112,115,116,119,
%U A368998 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
%N 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.
%C A368998 From _Antti Karttunen_, Jun 03 2024: (Start)
%C A368998 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.
%C A368998 Because both A003159 and A235992 are multiplicative semigroups, this is also: if m and n are in the sequence then so is m*n.
%C A368998 (End)
%H A368998 Antti Karttunen, <a href="/A368998/b368998.txt">Table of n, a(n) for n = 1..20000</a>
%o A368998 (PARI) isA368998 = A368997;
%Y A368998 Cf. A000290, A003415, A276085, A368995 (subsequence), A368997 (characteristic function), A368999 (complement).
%Y A368998 Positions of even terms in A342001 and in A373145.
%Y A368998 Intersection of A003159 and A235992.
%Y A368998 Disjoint union of A345452 and 2*A358776.
%K A368998 nonn
%O A368998 1,2
%A A368998 _Antti Karttunen_, Jan 14 2024
%E A368998 Alternative definition added as a new primary definition by _Antti Karttunen_, Jun 04 2024