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 A153799 #46 Mar 23 2024 13:34:31
%S A153799 8,5,8,4,0,7,3,4,6,4,1,0,2,0,6,7,6,1,5,3,7,3,5,6,6,1,6,7,2,0,4,9,7,1,
%T A153799 1,5,8,0,2,8,3,0,6,0,0,6,2,4,8,9,4,1,7,9,0,2,5,0,5,5,4,0,7,6,9,2,1,8,
%U A153799 3,5,9,3,7,1,3,7,9,1,0,0,1,3,7,1,9,6,5,1,7,4,6,5,7,8,8,2,9,3,2,0,1,7,8
%N A153799 Decimal expansion of 4 - Pi.
%C A153799 Given a square with a side measuring 2 units, having a circle with a radius of 2 units centered on one of its corners, and another circle also with a radius of 2 units centered on the most distant corner from the one on which the first circle is centered, there are two "zones" within the square that overlap with the area of only one of the circles. This number gives the area of either zone. - _Alonso del Arte_, Aug 01 2012
%C A153799 Area between a circle of radius 1 and the circumscribed square. - _Omar E. Pol_, Aug 02 2012
%C A153799 Perimeter of the unit square minus the circumference of its incircle. - _Jonathan Sondow_, Nov 23 2017
%H A153799 G. C. Greubel, <a href="/A153799/b153799.txt">Table of n, a(n) for n = 0..2000</a>
%H A153799 <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>
%F A153799 4 - Pi = (-1)(Pi - 4) = (-1)*Sum_{n >= 1} (4*(-1)^n/(2*n + 1)) = (-1)*arcsin(sin 4). - _Alonso del Arte_, Aug 01 2012
%F A153799 Equals Integral_{x=0..Pi} cos(x)^2/(1 + sin(x))^2 dx. - _Amiram Eldar_, Aug 21 2020
%F A153799 Equals Integral_{x=0..4} sqrt(x)/(4+x) dx. - _Andy Nicol_, Mar 23 2024
%e A153799 0.8584073464102067615373566167204971158...
%t A153799 RealDigits[4 - Pi, 10, 100][[1]] (* _Alonso del Arte_, Aug 01 2012 *)
%o A153799 (PARI) 4-Pi
%Y A153799 Essentially the same as A030644.
%Y A153799 Cf. A000796, A063448.
%K A153799 easy,nonn,cons
%O A153799 0,1
%A A153799 _Omar E. Pol_, Jan 25 2009