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 A083235 #14 Sep 24 2018 16:53:14
%S A083235 1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,2,1,1,
%T A083235 1,1,1,1,1,1,1,1,1,1,1,1,2,2,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
%U A083235 1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,1,1,1,1,1,1,1,1
%N A083235 First differences of A063742, the possible values for cototients.
%C A083235 Differences between consecutive numbers in the range of A051853.
%F A083235 a(n) = A063742(n+1) - A063742(n).
%e A083235 First missing number in A063742 is 10=A005278[1], so a[10]=2 is the first difference here > 1.
%t A083235 t0[x_] := Table[j, {j, 1, x}] t=Table[w-EulerPhi[w], {w, 1, 10000}]; u=Union[%]; Delete[u-RotateRight[u], 1]
%K A083235 nonn
%O A083235 1,10
%A A083235 _Labos Elemer_, May 20 2003
%E A083235 Edited by _N. J. A. Sloane_ at the suggestion of _Andrew S. Plewe_, Jun 23 2007