This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A373490 #11 Jun 10 2024 10:02:41 %S A373490 1,2,4,8,10,12,15,16,20,28,32,36,64,100,108,128,144,162,180,189,192, %T A373490 216,225,256,400,480,500,512,686,784,972,1000,1024,1250,1280,1296, %U A373490 1350,1728,1890,2048,2160,2304,2700,2835,2880,3375,3500,3600,3840,4032,4096,4500,4800,4860,5005,5096,5120,6300,6400,6480,6750 %N A373490 Numbers k for which A003415(k) is a multiple of A276085(k), where A003415 is the arithmetic derivative and A276085 is the primorial base log-function. %C A373490 Conjecture: if term present here is squarefree, then it must be a term of A369650: 1, 2, 10, 15, 5005, and possibly no others. %H A373490 Antti Karttunen, <a href="/A373490/b373490.txt">Table of n, a(n) for n = 1..233; terms <= 2^20</a> %o A373490 (PARI) isA373490 = A373489; %Y A373490 Cf. A003415, A276085, A373489 (characteristic function). %Y A373490 Subsequences: A000079, A369650. %Y A373490 After the initial 1, gives the positions of 0's in A373147. %Y A373490 Cf. also A373487, A373488. %K A373490 nonn %O A373490 1,2 %A A373490 _Antti Karttunen_, Jun 09 2024