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 A243597 #16 Jul 21 2025 02:41:19 %S A243597 2,2,9,8,4,8,8,4,7,0,6,5,9,3,0,1,4,1,2,9,9,5,3,1,6,9,6,2,7,8,5,1,1,6, %T A243597 9,8,1,3,3,8,4,4,7,8,9,6,9,1,0,3,8,8,8,6,1,6,4,9,5,1,3,7,2,3,0,9,4,4, %U A243597 9,8,0,2,6,1,2,7,6,4,1,1,7,7,4,1,0,2,4,0,7,1,9,5,6,4,0,8,4,5,5,3,2,8,2,1,4 %N A243597 Decimal expansion of the fraction of the full solid angle subtended by a cone with the polar angle of 1 radian. %C A243597 Given a right circular cone with polar angle theta, the fraction of the full solid angle it subtends is (1-cos(theta))/2. %H A243597 Stanislav Sykora, <a href="/A243597/b243597.txt">Table of n, a(n) for n = 0..2000</a> %H A243597 Wikipedia, <a href="http://en.wikipedia.org/wiki/Solid_angle">Solid angle</a> %H A243597 Wikipedia, <a href="http://en.wikipedia.org/wiki/Cone">Cone</a> %F A243597 Equals (1-cos(1))/2. %F A243597 Equals A243596/(4*Pi). %e A243597 0.22984884706593014129953169627851169813384478969103888616... %t A243597 RealDigits[(1-Cos[1])/2,10,120][[1]] (* _Harvey P. Dale_, Apr 14 2019 *) %o A243597 (PARI) (1-cos(1))/2 %Y A243597 Cf. A243596 (solid angle). %K A243597 nonn,cons,easy %O A243597 0,1 %A A243597 _Stanislav Sykora_, Jun 07 2014