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 A195720 #20 Nov 20 2024 23:40:04
%S A195720 1,1,5,0,2,6,1,9,9,1,5,1,0,9,3,1,4,9,1,3,4,3,0,5,9,1,7,5,7,2,6,5,3,6,
%T A195720 0,6,8,7,4,7,5,4,5,3,0,6,8,6,7,6,3,3,3,0,0,5,9,8,2,1,0,8,9,3,8,0,7,8,
%U A195720 6,3,5,5,1,4,0,4,9,3,5,8,1,9,0,5,4,7,5,0,4,1,0,2,4,5,2,6,6,0,1,7
%N A195720 Decimal expansion of arccos(sqrt(1/6)) and of arcsin(sqrt(5/6)) and arctan(sqrt(5)).
%H A195720 G. C. Greubel, <a href="/A195720/b195720.txt">Table of n, a(n) for n = 1..5000</a>
%H A195720 Kunle Adegoke, <a href="http://arxiv.org/abs/1603.08097">Infinite arctangent sums involving Fibonacci and Lucas numbers</a>, arXiv:1603.08097 [math.NT], 2016.
%H A195720 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%F A195720 Equals Sum_{k >= 1} sqrt(5)/L(2n) where L=A000032. See also A005248. - _Michel Marcus_, Mar 29 2016
%e A195720 arccos(sqrt(1/6)) = 1.150261991510931...
%t A195720 r = Sqrt[1/6]; RealDigits[ArcCos[r], 10, 100][[1]]
%o A195720 (PARI) atan(sqrt(5)) \\ _Michel Marcus_, Mar 29 2016
%o A195720 (Magma) [Arccos(Sqrt(1/6))]; // _G. C. Greubel_, Nov 23 2017
%Y A195720 Cf. A188595, A195721, A195722.
%K A195720 nonn,cons
%O A195720 1,3
%A A195720 _Clark Kimberling_, Sep 23 2011