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 A114609 #17 Feb 16 2025 08:32:59
%S A114609 3,1,4,1,5,9,2,6,5,3,5,9,5,1,8,2,3,8,3,2,8,8,4,2,3,9,5,1,3,3,7,1,9,5,
%T A114609 7,4,6,4,7,4,3,0,2,5,6,3,7,8,1,8,2,2,2,9,2,9,0,4,4,4,3,1,7,2,5,0,9,1,
%U A114609 3,0,3,0,4,8,2,7,0,4,2,4,1,7,6,1,0,1,2,3,7,5,1,5,3,5,6,7,5,8,5,1,1,9
%N A114609 Decimal expansion of Sum_{k=-infinity..+infinity} log(2)/(2^(-k/2) + 2^(k/2)).
%C A114609 Differs from Pi by 5.3*10^-12.
%H A114609 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/AlmostInteger.html">Almost Integer</a>
%e A114609 3.14159265359518238328842...
%t A114609 almostPi = Log[2]/2 + 2*Log[2]*NSum[1/(2^(-k/2) + 2^(k/2)), {k, 1, Infinity}, WorkingPrecision -> 110, NSumTerms -> 100]; RealDigits[almostPi, 10, 102] // First (* _Jean-François Alcover_, Feb 07 2013 *)
%K A114609 nonn,cons
%O A114609 0,1
%A A114609 _Eric W. Weisstein_, Dec 15 2005