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 A216548 #15 Feb 04 2025 10:11:02
%S A216548 3,1,4,1,5,9,2,4,5,3,5,8,9,7,9,3,2,3,8,4,6,4,6,4,3,3,8,3,2,7,9,5,0,2,
%T A216548 7,8,4,1,9,7,1,6,9,3,9,9,3,8,7,3,0,5,8,2,0,9,7,4,9,4,1,8,2,2,3,0,7,8,
%U A216548 1,6,4,0,7,2,9,6,6,2,8,9,9,8,6,2,7,4,9,4,2,7,2,3,4,2,1,1,7,4,6,6,7,0,4,1,1,0,0,8,6,1,2,5,4,5,2,0,6,3,7,4,7,5,7,4,8
%N A216548 Decimal expansion of 4*Sum_{k=1..5000000} (-1)^(k-1)/(2k-1).
%C A216548 An approximation to Pi. The constant is rational, by definition (a product of finitely many rational numbers).
%H A216548 J. M. Borwein, P. B. Borwein and K. Dilcher, <a href="http://www.jstor.org/stable/2324715">Pi, Euler numbers and asymptotic expansions</a>, Amer. Math. Monthly, 96 (1989), 681-687.
%H A216548 J. M. Borwein and R. M. Corless, <a href="http://www.cecm.sfu.ca/~jborwein/sloane/sloane.html">Review of "An Encyclopedia of Integer Sequences" by N. J. A. Sloane and Simon Plouffe</a>, SIAM Review, 38 (1996), 333-337.
%H A216548 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>.
%e A216548 3.1415924535897932384646433832795027841971693993873058209749418223...
%Y A216548 Cf. A000796, A216542, A013706, A216543, A216544, A216545, A013705, A216546, A216547, A216548.
%Y A216548 Cf. also A195793.
%K A216548 cons,nonn,easy
%O A216548 1,1
%A A216548 _N. J. A. Sloane_, Sep 08 2012