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 A300073 #20 Nov 04 2018 20:32:13 %S A300073 1,2,0,2,0,9,2,6,8,3,2,5,3,6,5,9,0,6,7,1,3,7,0,7,2,7,1,0,1,0,4,2,9,8, %T A300073 5,2,3,6,2,1,7,1,5,6,1,8,8,2,1,7,4,3,0,4,9,9,0,0,1,7,5,2,9,6,4,0,3,2, %U A300073 2,1,2,5,5,2,2,0,6,0,6,6,8,1,7,0,9,5,6,0,0,4,6,6,7,3,9,4,9,6,3,6 %N A300073 Decimal expansion of the member z of a triple (x, y, z) satisfying a certain historical system of three equations with negative y. %C A300073 See A300070 and A300072 for the system of equations, the Havil reference and links to Abū Kāmil. %C A300073 The present solution is x = x2 = 10*A248750, -y = -y2 = A300072, z = z2 = present entry. %F A300073 z2 = 5*(phi + (phi - 1)*sqrt(phi)), with the golden section phi = (1 + sqrt(5))/2 = A001622. %F A300073 z2 = 10 - 2*y2 + (1/50)*y2^3, with y2 = -A300072. %e A300073 z2 = 12.02092683253659067137072710104298523621715618821743049900175296403... %e A300073 z2/5 = 2.4041853665073181342741454202085970472434312376434860998003505928... %t A300073 RealDigits[5 (GoldenRatio + (GoldenRatio - 1) Sqrt[GoldenRatio]), 10, 100][[1]] (* _Bruno Berselli_, Mar 02 2018 *) %Y A300073 Cf. A001622, A248750, A248752, A300070, A300071, A300072. %K A300073 nonn,cons,easy %O A300073 2,2 %A A300073 _Wolfdieter Lang_, Mar 02 2018