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 A066683 #8 Feb 04 2021 18:17:16
%S A066683 0,1,2,2,3,3,4,5,5,5,6,7,8,8,8,8,9,10,11,11,11,11,12,12,12,12,13,13,
%T A066683 14,15,16,16,16,16,16,16,17,17,17,17,18,18,19,19,20,20,21,21,21,22,22,
%U A066683 22,23,23,23,23,23,23,24,24,25,25,26,26,26,26
%N A066683 Number of badly sieved numbers <= n.
%F A066683 a(n) = Sum_{k=1..n} A099104(k).
%Y A066683 Cf. A099104, A066680, A000720.
%K A066683 nonn
%O A066683 1,3
%A A066683 _Reinhard Zumkeller_, Dec 31 2001