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 A039920 #12 Feb 28 2021 19:54:00
%S A039920 7,71,718,7182,71828,718281,7182818,71828182,718281828,7182818284,
%T A039920 71828182845,718281828459,7182818284590,71828182845904,
%U A039920 718281828459045,7182818284590452,71828182845904523,718281828459045235,7182818284590452353,71828182845904523536
%N A039920 Concatenation of the first n decimal digits of e-2.
%t A039920 Module[{nn=20,c},c=Rest[RealDigits[E,10,nn][[1]]];Table[FromDigits[ Take[ c,n]],{n,nn-1}]] (* _Harvey P. Dale_, Jun 08 2015 *)
%Y A039920 Cf. A001113, A039916.
%K A039920 base,nonn
%O A039920 1,1
%A A039920 _Felice Russo_
%E A039920 More terms from _Sean A. Irvine_, Feb 28 2021