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 A085011 #16 May 28 2021 06:14:15
%S A085011 8,3,8,8,4,4,8,8,3,5,9,0,2,1,5,1,9,5,4,1,9,9,1,2,2,1,5,4,0,5,9,4,8,5,
%T A085011 0,4,4,6,7,9,0,6,4,6,8,7,8,5,3,3,3,4,9,8,1,6,0,8,9,9,8,3,3,2,6,3,5,4,
%U A085011 4,1,0,1,7,4,5,4,1,8,3,8,7,8,2,0,0,4,6,4,9,0,9,4,8,4,7,6,3,9,1,0,0,5,7,1
%N A085011 Decimal expansion of 4*Product_{k>=0} (1 - 1/(2^k+1)).
%F A085011 Equals 4 * A083864. - _Amiram Eldar_, May 28 2021
%e A085011 0.8388448835902...
%o A085011 (PARI) 4*prod(k=0,1000,1-1./(2^k+1))
%o A085011 (PARI) 4*prodinf(k=0, 1-1/(2^k+1)) \\ _Amiram Eldar_, May 28 2021
%Y A085011 Cf. A083864.
%K A085011 cons,nonn
%O A085011 0,1
%A A085011 _Benoit Cloitre_, Jun 19 2003
%E A085011 Leading zero removed by _R. J. Mathar_, Feb 05 2009