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 A272795 #41 Apr 21 2025 12:16:18
%S A272795 9,5,8,8,5,1,0,7,7,2,0,8,4,0,6,0,0,0,5,4,6,5,7,5,8,7,0,4,3,1,1,4,2,7,
%T A272795 7,6,1,6,3,6,0,6,7,3,5,8,8,1,2,0,1,3,5,0,3,7,7,2,3,3,2,2,6,2,5,1,0,7,
%U A272795 0,0,0,0,5,7,5,6,2,9,6,6,4,4,1,9,2,6,2
%N A272795 Decimal expansion of 2*sin(1/2).
%C A272795 The length of the line underlying an arc of one radian with radius 1 (i.e., the linear distance for ends of an arc length 1 having same length as radius).
%F A272795 Equals i*e^(-i/2) - i*e^(i/2).
%F A272795 Equals 2*A201504.
%F A272795 Equals Sum_{k>=0} 2*(-1)^k*(1/2 - Pi/2)^(2*k)/(2*k)!. - _Ilya Gutkovskiy_, May 22 2016
%F A272795 Equals sqrt(A371935). - _Hugo Pfoertner_, Apr 21 2025
%e A272795 0.958851077208406000546575870431142776163606735881201350377...
%t A272795 RealDigits[2 Sin[1/2], 10, 100][[1]] (* _Ilya Gutkovskiy_, May 22 2016 *)
%o A272795 (PARI) 2*sin(1/2) \\ _Stefano Spezia_, Apr 21 2025
%Y A272795 Cf. A201504, A371935.
%K A272795 nonn,cons
%O A272795 0,1
%A A272795 _Peter M. Chema_, May 22 2016
%E A272795 More digits from _Jon E. Schoenfield_, Mar 15 2018