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 A102559 #15 Apr 06 2025 05:30:54
%S A102559 4,8,20,560,560,440,7280,160160,2722720,51731680,51731680,45762640,
%T A102559 1487285800,5949143200,86262576400,10696559473600,368846878400,
%U A102559 562976814400,395772700523200,395772700523200,16226680721451200
%N A102559 Denominator of the probability that (2n+1)-dimensional Gaussian random triangle has an obtuse angle.
%H A102559 G. C. Greubel, <a href="/A102559/b102559.txt">Table of n, a(n) for n = 1..1000</a>
%H A102559 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/GaussianTrianglePicking.html">Gaussian Triangle Picking</a>
%F A102559 From _G. C. Greubel_, Feb 01 2025: (Start)
%F A102559 a(n) = denominator( p(n) ), where p(n) = Pi/sqrt(3) - (3^(n+1)/(2*binomial(2*n, n))) * Sum_{k>=0} binomial(2*k, k)*(3/16)^k/(2*k + 2*n + 1).
%F A102559 a(n) = denominator( p(n) ), where p(n) = Pi/sqrt(3) - (3^(n+1)/(2*(2*n+1)*binomial(2*n,n))) * Hypergeometric2F1([1/2, 1/2 + n], [3/2+n], 3/4). (End)
%e A102559 1 - (3*sqrt(3))/(4*Pi), 1 - (9*sqrt(3))/(8*Pi), 1 - (27*sqrt(3))/(20*Pi), ...
%t A102559 Table[Denominator[Simplify[Pi/Sqrt[3] -(3^(n+1)*Hypergeometric2F1[1/2, 1/2+ n, 3/2+n, 3/4])/(2*(2*n+1)*Binomial[2*n,n])]], {n,30}] (* _G. C. Greubel_, Feb 01 2025 *)
%Y A102559 Cf. A102556, A102557, A102558 (numerator).
%K A102559 nonn,frac
%O A102559 1,1
%A A102559 _Eric W. Weisstein_, Jan 14 2005