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 A181673 #18 Jul 07 2023 13:33:02
%S A181673 0,8,8,9,9,0,9,0,0,0,8,9,9,1,0,9,8,9,9,0,1,0,9,0,0,0,9,9,8,8,9,0,1,1,
%T A181673 0,9,9,1,0,9,8,8,9,0,0,0,9,0,0,0,0,9,9,0,1,0,1,0,8,9,9,1,0,0,0,8,9,0,
%U A181673 0,8,8,9,9,1,0,0,0,8,9,0,0,0,9,0,1,1,0,9,9
%N A181673 Decimal expansion of Sum_{n>=1} moebius(n)*(1/10)^n.
%e A181673 0.088990900089910989901090009988901109910...
%t A181673 RealDigits[ Sum[ N[ MoebiusMu[n] 10^-n, 128], {n, 120}], 10, 111][[1]] (* _Robert G. Wilson v_, Feb 21 2014 *)
%o A181673 (PARI) sum(n=1,default(realprecision)+1,moebius(n)/10.^n) \\ _Charles R Greathouse IV_, Feb 13 2011
%Y A181673 Cf. A008683, A238270, A238271, A238273.
%K A181673 cons,nonn
%O A181673 0,2
%A A181673 _Mats Granvik_, Nov 04 2010
%E A181673 Corrected by _Charles R Greathouse IV_, May 27 2015