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 A189969 #12 Sep 08 2022 08:45:56
%S A189969 3,0,8,8,7,6,0,4,3,2,4,4,5,1,3,2,6,4,8,2,2,5,6,9,7,2,0,6,4,6,9,6,4,5,
%T A189969 4,1,6,7,6,3,8,4,4,8,0,8,5,4,0,2,3,1,1,3,8,8,8,7,9,7,9,6,7,9,3,5,5,8,
%U A189969 7,8,5,7,3,5,7,9,1,4,7,0,9,5,3,4,2,1,5,0,4,2,1,6,1,2,3,9,4,3,9,0,9,3,0,8,5,1,2,7,7,3,4,4,9,9,0,0,1,9,6,1
%N A189969 Decimal expansion of (7 + sqrt(133))/6, which has periodic continued fractions [3,11,3,1,3,11,3,1,...] and [7/3, 1, 7/3, 1, ...].
%C A189969 Let R denote a rectangle whose shape (i.e., length/width) is (7+sqrt(133))/6. This rectangle can be partitioned into squares in a manner that matches the continued fraction [3,11,3,1,3,11,3,1,...]. It can also be partitioned into rectangles of shape 3/2 and 3 so as to match the continued fraction [7/3, 1, 7/3, 1, ...]. For details, see A188635.
%H A189969 G. C. Greubel, <a href="/A189969/b189969.txt">Table of n, a(n) for n = 1..10000</a>
%e A189969 3.088760432445132648225697206469645416764...
%t A189969 FromContinuedFraction[{7/3, 1, {7/3, 1}}]
%t A189969 ContinuedFraction[%, 25] (* [3,11,3,1,3,11,3,1,...] *)
%t A189969 RealDigits[N[%%, 120]] (* A189969 *)
%t A189969 N[%%%, 40]
%o A189969 (PARI) (7 + sqrt(133))/6 \\ _G. C. Greubel_, Jan 12 2018
%o A189969 (Magma) (7 + Sqrt(133))/6 // _G. C. Greubel_, Jan 12 2018
%Y A189969 Cf. A188635, A188967.
%K A189969 nonn,cons
%O A189969 1,1
%A A189969 _Clark Kimberling_, May 05 2011
%E A189969 Typo in name corrected by _G. C. Greubel_, Jan 12 2018