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 A157258 #13 Feb 07 2025 12:38:09
%S A157258 9,8,2,8,4,2,7,1,2,4,7,4,6,1,9,0,0,9,7,6,0,3,3,7,7,4,4,8,4,1,9,3,9,6,
%T A157258 1,5,7,1,3,9,3,4,3,7,5,0,7,5,3,8,9,6,1,4,6,3,5,3,3,5,9,4,7,5,9,8,1,4,
%U A157258 6,4,9,5,6,9,2,4,2,1,4,0,7,7,7,0,0,7,7,5,0,6,8,6,5,5,2,8,3,1,4,5,4,7,0,0,2
%N A157258 Decimal expansion of 7 + 2*sqrt(2).
%C A157258 lim_{n -> infinity} b(n)/b(n-1) = (7+2*sqrt(2))/(7-2*sqrt(2)) for n mod 3 = {1, 2}, b = A129288.
%C A157258 lim_{n -> infinity} b(n)/b(n-1) = (7+2*sqrt(2))/(7-2*sqrt(2)) for n mod 3 = {0, 2}, b = A157257.
%H A157258 G. C. Greubel, <a href="/A157258/b157258.txt">Table of n, a(n) for n = 1..5000</a>
%H A157258 <a href="/index/Al#algebraic_02">Index entries for algebraic numbers, degree 2</a>.
%F A157258 Equals 4 + A156035. - _R. J. Mathar_, Feb 27 2009
%e A157258 7 + 2*sqrt(2) = 9.82842712474619009760...
%t A157258 RealDigits[7+2Sqrt[2],10,120][[1]] (* _Harvey P. Dale_, Mar 20 2011 *)
%o A157258 (PARI) 7+2*sqrt(2) \\ _G. C. Greubel_, Nov 28 2017
%o A157258 (Magma) [7+2*Sqrt(2)]; // _G. C. Greubel_, Nov 28 2017
%Y A157258 Cf. A129288, A157257, A157259 (decimal expansion of 7-2*sqrt(2)), A157260 (decimal expansion of (7+2*sqrt(2))/(7-2*sqrt(2))).
%K A157258 cons,nonn
%O A157258 1,1
%A A157258 _Klaus Brockhaus_, Feb 26 2009