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 A186444 #18 Jun 25 2022 00:40:51 %S A186444 0,0,1,1,1,2,2,2,2,2,2,3,3,3,4,4,4,4,4,4,5,5,5,6,6,6,7,7,7,8,8,8,9,9, %T A186444 9,9,9,9,10,10,10,11,11,11,11,11,11,12,12,12,13,13,13,14,14,14,15,15, %U A186444 15,16,16,16,16,16,16,17,17,17,18,18,18,18,18,18,19 %N A186444 The count of numbers <= n for which 3 is an infinitary divisor. %C A186444 For the definition of infinitary divisors, see A037445. %C A186444 The sequence is the partial sums of the characteristic function of the numbers with 3 as one of the infinitary divisors; these are 3, 6, 12, 15, 21, 24, 27, 30 etc, apparently shown in A145204. - _R. J. Mathar_, Feb 28 2011 %H A186444 Amiram Eldar, <a href="/A186444/b186444.txt">Table of n, a(n) for n = 1..10000</a> %F A186444 a(n) = floor(n/3) - a(floor(n/3)). %F A186444 a(n) = floor(n/3) - floor(n/9) + floor(n/27) - .... %F A186444 a(n) grows as n/4 as n tends to infinity. %p A186444 A186444 := proc(n) local a,k ; option remember; if n< 3 then 0; else floor(n/3) -procname(floor(n/3)) ; end if; end proc: # _R. J. Mathar_, Feb 28 2011 %Y A186444 Cf. A123087, A037445. %Y A186444 Partial sums of A182581. %K A186444 nonn %O A186444 1,6 %A A186444 _Vladimir Shevelev_, Feb 21 2011