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 A008716 #10 Jul 08 2025 01:20:45
%S A008716 10,11,12,13,14,15,16,17,18,19,21,23,25,31,34,103,201,10011,
%T A008716 1111111111111111111
%N A008716 19 in base 19-n.
%t A008716 Append[Table[FromDigits[IntegerDigits[19, 19 - n]], {n, 0, 17}], FromDigits[Table[1, {19}]]] (* _T. D. Noe_, Feb 23 2013 *)
%K A008716 fini,nonn,base,full
%O A008716 0,1
%A A008716 _N. J. A. Sloane_