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 A300270 #20 May 16 2025 07:29:36
%S A300270 1,1,1,1,1,2,2,2,2,3,3,4,4,5,6,6,6,7,7,8,9,10,10,11,11,12,12,13,13,13,
%T A300270 13,13,14,15,16,17,17,18,19,20,20,20,20,21,22,23,23,24,24,25,26,27,27,
%U A300270 28,29,30,31,32,32,32,32,33,34,34,35,35,35,36,37,37,37,38,38,39,40,41,42,42,42,43,43,44,44,44,45,46,47,48,48,48
%N A300270 a(n) = Sum_{1 <= i <= j <= n} mu(i*j)*floor((n/i)/j).
%C A300270 We have Sum_{k=1..n} mu(k)*floor(n/k) = 1 and lim_{n -> infinity} Sum_{1 <= i <= j <= n} (mu(i*j)/i)/j = 1/2.
%F A300270 a(n) ~ n/2 (n->infinity).
%F A300270 a(n) = (A174863(n) + n)/2. - _Ridouane Oudra_, May 16 2025
%o A300270 (PARI) a(n) = sum(j=1, n, sum(i=1, j, moebius(i*j)*floor(n/i/j)))
%Y A300270 Cf. A174863, A008683.
%K A300270 nonn
%O A300270 1,6
%A A300270 _Benoit Cloitre_, Mar 01 2018