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 A197691 #13 Mar 19 2025 11:04:42
%S A197691 1,8,9,6,3,6,7,4,8,2,4,8,6,9,4,0,3,6,3,3,6,1,0,7,6,7,2,2,6,1,2,2,3,2,
%T A197691 1,6,0,3,4,6,0,6,5,9,1,4,1,0,1,3,2,7,4,9,1,6,7,2,4,7,0,5,3,4,4,5,6,3,
%U A197691 7,0,3,4,2,7,5,2,3,9,3,4,4,0,8,0,1,5,8,2,9,3,5,0,3,8,3,8,9,4,3
%N A197691 Decimal expansion of Pi/(4 + 4*Pi).
%C A197691 Least x > 0 such that sin(b*x) = cos(c*x) (and also sin(c*x) = cos(b*x)), where b=2 and c=2*Pi; see the Mathematica program for a graph and A197682 for a discussion and guide to related sequences.
%H A197691 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%e A197691 0.1896367482486940363361076722612232160346065914...
%t A197691 b = 2; c = 2 Pi;
%t A197691 t = x /. FindRoot[Sin[b*x] == Cos[c*x], {x, .1, .2}]
%t A197691 N[Pi/(2*b + 2*c), 110]
%t A197691 RealDigits[%] (* A197691 *)
%t A197691 Simplify[Pi/(2*b + 2*c)]
%t A197691 Plot[{Sin[b*x], Cos[c*x]}, {x, 0, Pi/2}]
%t A197691 RealDigits[Pi/(4+4Pi),10,120][[1]] (* _Harvey P. Dale_, Mar 19 2025 *)
%Y A197691 Cf. A197682.
%K A197691 nonn,cons
%O A197691 0,2
%A A197691 _Clark Kimberling_, Oct 17 2011