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 A073821 #23 Nov 30 2020 08:49:12
%S A073821 4,4,6,3,8,9,9,6,5,8,9,6,5,3,4,5,0,7,0,4,7,6,8,1,7,9,5,1,9,2,6,4,2,6,
%T A073821 6,9,7,7,6,2,5,3,1,4,7,4,0,0,3,8,7,8,2,2,8,6,1,1,9,8,9,8,6,5,4,9,5,1,
%U A073821 4,8,9,3,1,4,4,3,6,7,5,6,2,5,6,8,6,0,7,6,8,8,0,0,6,9,9,5,1,3,6,5,8,2,2,7
%N A073821 Decimal expansion of number with continued fraction expansion 0, 2, 4, 6, ... (the even numbers).
%H A073821 Lucas A. Brown, <a href="/A073821/b073821.txt">Table of n, a(n) for n = 0..1000</a>
%F A073821 BesselI(1, 1)/BesselI(0, 1) (courtesy of the Inverse Symbolic Calculator).
%e A073821 0.44638996589653450704768179519...
%t A073821 RealDigits[FromContinuedFraction[2Range[0,200]],10,120][[1]] (* _Harvey P. Dale_, Oct 30 2011 *)
%o A073821 (PARI) dec_exp(v)= {my(w=contfracpnqn(v)); w[1,1]/w[2,1]+0.0; }
%o A073821 dec_exp(vector(2000,i,2*(i-1)))
%Y A073821 Cf. A005843 (even numbers), A052119 (continued fraction exp. is 0, 1, 2, 3, ...), A073747 (coth(1), continued fraction exp. is odd numbers).
%K A073821 cons,nonn
%O A073821 0,1
%A A073821 _Rick L. Shepherd_, Aug 12 2002