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 A019762 #45 Apr 20 2024 10:27:05
%S A019762 5,4,3,6,5,6,3,6,5,6,9,1,8,0,9,0,4,7,0,7,2,0,5,7,4,9,4,2,7,0,5,3,2,4,
%T A019762 9,9,5,5,1,4,4,9,4,1,8,7,3,9,9,9,1,9,1,4,9,9,3,3,9,3,5,2,5,5,4,4,8,1,
%U A019762 5,3,2,6,0,7,0,7,0,9,5,1,8,9,1,4,2,7,6,4,3,5,7,0,5,0,3,3,2,8,5,4,8,5,4,9,3
%N A019762 Decimal expansion of 2*e.
%C A019762 Simple continued fraction is A081750. - _Michael Somos_, May 07 2012
%C A019762 Equals Sum_{n>=1} n^2/n!. - _Arkadiusz Wesolowski_, Mar 11 2013
%C A019762 Equals lim_{x->1} (x*e^x - e)/(x-1). Also 2*e = Sum_{n>=0} Sum_{k=0..n} 1/n!. - _Richard R. Forberg_, Dec 23 2014
%C A019762 Equals 1 + (2/1) + (3/2/1) + (4/3/2/1) + (5/4/3/2/1) + (6/5/4/3/2/1) + ... . - _Davide Rotondo_, Apr 07 2024
%H A019762 Ivan Panchenko, <a href="/A019762/b019762.txt">Table of n, a(n) for n = 1..1000</a>
%H A019762 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%e A019762 2*e = 5.43656365691809047072057494270532499551449418739991914993...
%t A019762 RealDigits[N[2*E, 105]][[1]] (* _Arkadiusz Wesolowski_, Mar 11 2013 *)
%o A019762 (PARI) 2*exp(1) \\ _Charles R Greathouse IV_, Oct 02 2022
%Y A019762 Cf. A001113, A081750 (continued fraction), A081749 (continued fraction of e/5 = 0.543...).
%K A019762 nonn,cons
%O A019762 1,1
%A A019762 _N. J. A. Sloane_