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 A196816 #20 Feb 16 2025 08:33:15
%S A196816 1,1,0,2,5,0,5,8,2,4,4,0,6,4,1,6,0,4,3,5,7,1,0,5,0,1,5,5,0,2,2,2,2,4,
%T A196816 0,7,3,8,8,4,8,1,0,5,8,2,0,0,9,7,7,5,1,1,6,0,8,5,3,7,5,3,7,1,4,7,6,3,
%U A196816 5,2,2,9,5,8,5,5,8,8,3,9,6,0,3,3,1,5,5,3,6,1,0,8,1,4,9,4,8,3,2,8
%N A196816 Decimal expansion of the least x>0 satisfying 1/(1+x^2)=cos(x).
%H A196816 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/WitchofAgnesi.html">Witch of Agnesi</a>
%H A196816 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>.
%e A196816 1.10250582440641604357105015502222407388481058200...
%t A196816 Plot[{1/(1 + x^2), Cos[x], 2 Cos[x], 3 Cos[x], 4 Cos[x]}, {x, 0, 2}]
%t A196816 t = x /. FindRoot[1 == (1 + x^2) Cos[x], {x, 1, 1.5}, WorkingPrecision -> 100]
%t A196816 RealDigits[t]
%o A196816 (PARI) solve(x=1, 1.5, cos(x)*(1+x^2) - 1) \\ _Michel Marcus_, Feb 10 2015
%Y A196816 Cf. A196914, A196817, A196818, A196819, A196820, A196821.
%K A196816 nonn,cons
%O A196816 1,4
%A A196816 _Clark Kimberling_, Oct 06 2011