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 A070891 #8 May 11 2023 18:19:24
%S A070891 30,15,105,210,2310,5005,1616615,9699690,223092870,111546435,
%T A070891 2156564410,100280245065,3710369067405,7420738134810,6541380665835015
%N A070891 Denominator of Sum_{k=1..n} mu(k)/k when it changes sign.
%o A070891 (PARI) t = 0; v = []; for( n = 1, 80, t1 = t; t = t + moebius( n) / n; if( t * t1 < 0, v = concat( v, denominator( t)), )); v
%Y A070891 Cf. A070890, A070888, A070889.
%K A070891 nonn,frac
%O A070891 1,1
%A A070891 _Donald S. McDonald_, May 17 2002