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 A368613 #8 Jan 01 2024 22:28:38
%S A368613 0,0,1,3,5,9,12,18,23,29,33,44,49,58,67,79,85,100,107,123,135,147,155,
%T A368613 179,190,204,218,238,247,273,283,306,322,339,355,388,399,418,436,468,
%U A368613 480,514,527,555,582,604,618,663,681,711,733,764,779,819,841,881,905,930
%N A368613 a(n) = Sum_{k=2..n} pi(k-1) * floor(n/k).
%F A368613 a(n) = A368611(n) - A013939(n).
%t A368613 Table[Sum[PrimePi[k - 1] Floor[n/k], {k, 2, n}], {n, 100}]
%Y A368613 Cf. A000720 (pi), A013939, A046992, A368610, A368611, A368612.
%K A368613 nonn,easy
%O A368613 1,4
%A A368613 _Wesley Ivan Hurt_, Dec 31 2023