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 A339919 #12 Dec 23 2020 06:44:26
%S A339919 0,0,0,1,1,3,1,5,4,4,5,9,5,7,10,10,8,13,8,16,13,11,15,19,14,15,18,21,
%T A339919 18,22,17,23,22,22,26,30,18,24,29,31,28,31,26,32,33,29,32,42,32,35,34,
%U A339919 36,39,41,40,42,37,40,41,53,38,44,49,47,47,47,43,53,52
%N A339919 a(n) = Sum_{k=1..n} (floor(3*n/k) - 3*floor(n/k)).
%C A339919 In general, for m>=1, Sum_{k=1..n} (floor(m*n/k) - m*floor(n/k)) ~ m*n * (log(m) - H(m) + 1), where H(m) = A001008(m)/A002805(m) is the m-th harmonic number.
%H A339919 Vaclav Kotesovec, <a href="/A339919/b339919.txt">Table of n, a(n) for n = 0..10000</a>
%F A339919 a(n) ~ (3*log(3) - 5/2) * n.
%t A339919 Table[Sum[Floor[3*n/k] - 3*Floor[n/k], {k, 1, n}], {n, 0, 100}]
%o A339919 (PARI) a(n) = sum(k=1, n, floor(3*n/k) - 3*floor(n/k)); \\ _Michel Marcus_, Dec 23 2020
%Y A339919 Cf. A006218, A059851, A075989, A339918.
%K A339919 nonn
%O A339919 0,6
%A A339919 _Vaclav Kotesovec_, Dec 23 2020