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 A028833 #12 Nov 10 2021 07:06:42
%S A028833 0,0,0,0,0,0,2,0,0,0,0,0,3,1,0,0,0,0,2,0,3,2,1,0,0,0,0,1,2,0,4,2,1,1,
%T A028833 0,0,0,0,0,0,1,0,6,5,3,7,1,0,0,0,0,2,2,2,2,0,3,5,2,1,6,1,0,0,0,0,5,0,
%U A028833 4,3,4,0,4,3,2,7,2,1,1,0,0,0,0,0,2,6,0,3,2,0,5,4,6,10,1,1,8,1,0,0,0,0
%N A028833 Index of redundancy in period of continued fraction for sqrt(n).
%H A028833 Amiram Eldar, <a href="/A028833/b028833.txt">Table of n, a(n) for n = 1..10000</a>
%F A028833 a(n) = A003285(n) - A028832(n).
%t A028833 a[n_] := If[IntegerQ[Sqrt[n]], 0, Length[p = ContinuedFraction[Sqrt[n]] // Last] - Length[p // Union]]; Table[a[n], {n, 1, 102}] (* _Jean-François Alcover_, Dec 26 2012 *)
%Y A028833 Cf. A028832, A003285.
%K A028833 nonn,nice
%O A028833 1,7
%A A028833 _Olivier Gérard_