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 A157215 #9 Aug 21 2023 12:36:59
%S A157215 1,0,9,2,8,9,3,2,1,8,8,1,3,4,5,2,4,7,5,5,9,9,1,5,5,6,3,7,8,9,5,1,5,0,
%T A157215 9,6,0,7,1,5,1,6,4,0,6,2,3,1,1,5,2,5,9,6,3,4,1,1,6,6,0,1,3,1,0,0,4,6,
%U A157215 3,3,7,6,0,7,6,8,9,4,6,4,8,0,5,7,4,8,0,6,2,3,2,8,3,6,1,7,9,2,1,3,6,3,2,4,9
%N A157215 Decimal expansion of 18 - 5*sqrt(2).
%C A157215 lim_{n -> infinity} b(n)/b(n-1) = (18+5*sqrt(2))/(18-5*sqrt(2)) for n mod 3 = {1, 2}, b = A129544.
%C A157215 lim_{n -> infinity} b(n)/b(n-1) = (18+5*sqrt(2))/(18-5*sqrt(2)) for n mod 3 = {0, 2}, b = A157213.
%H A157215 G. C. Greubel, <a href="/A157215/b157215.txt">Table of n, a(n) for n = 2..5001</a>
%H A157215 <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a>
%e A157215 18 - 5*sqrt(2) = 10.92893218813452475599...
%t A157215 RealDigits[18 - 5*Sqrt[2], 10, 50][[1]] (* _G. C. Greubel_, Nov 28 2017 *)
%o A157215 (PARI) 18 - 5*sqrt(2) \\ _G. C. Greubel_, Nov 28 2017
%o A157215 (Magma) [18 - 5*Sqrt(2)]; // _G. C. Greubel_, Nov 28 2017
%Y A157215 Cf. A129544, A157213, A157214 (decimal expansion of 18+5*sqrt(2)), A157216 (decimal expansion of (18-5*sqrt(2))/(18+5*sqrt(2))).
%K A157215 cons,nonn
%O A157215 2,3
%A A157215 _Klaus Brockhaus_, Feb 25 2009