cp's OEIS Frontend

A373488 Nonprime natural numbers k such that A276085(k) is a multiple of A003415(k), where A003415 is the arithmetic derivative and A276085 is the primorial base log-function.

%I A373488 #7 Jun 09 2024 22:15:47
%S A373488 1,10,15,28,35,91,143,155,161,187,203,209,215,221,295,299,319,323,329,
%T A373488 341,371,377,391,403,437,515,538,559,581,611,649,667,689,703,707,731,
%U A373488 779,803,851,869,893,899,901,923,979,989,1037,1073,1081,1121,1139,1147,1189,1199,1207,1219,1261,1363,1391,1403,1457,1498
%N A373488 Nonprime natural numbers k such that A276085(k) is a multiple of A003415(k), where A003415 is the arithmetic derivative and A276085 is the primorial base log-function.
%C A373488 Nonsquarefree terms are rare: only 3 less than 2^20: 28, 33212, 855523.
%H A373488 Antti Karttunen, <a href="/A373488/b373488.txt">Table of n, a(n) for n = 1..25127</a>
%o A373488 (PARI) isA373488(n) = (!isprime(n) && A373486(n));
%Y A373488 Setwise difference A373487 \ A000040.
%Y A373488 Cf. A003415, A276085, A369650, A373486.
%K A373488 nonn
%O A373488 1,2
%A A373488 _Antti Karttunen_, Jun 09 2024