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 A255405 #20 May 23 2024 06:30:05
%S A255405 1,1,1,1,1,2,2,2,2,3,3,4,4,5,6,6,7,8,9,11,12,14,16,18,20,23,26,29,33,
%T A255405 37,42,47,53,60,68,77,87,98,111,125,141,159,180,203,229,258,292,329,
%U A255405 371,419,473,534,602,680,767,865,977,1102,1244,1403,1584,1787,2016,2275,2567
%N A255405 a(n) = floor((2/sqrt(Pi))^n).
%C A255405 Inspired by squaring the circle and Vitruvian Man, but starting with a unit circle and a square whose sides are of length sqrt(Pi), A002161. a(n) is the curvature (rounded down) of the n-th circle. See illustrations in the links.
%H A255405 G. C. Greubel, <a href="/A255405/b255405.txt">Table of n, a(n) for n = 0..5000</a>
%H A255405 Kival Ngaokrajang, <a href="/A255405/a255405.pdf">Illustration of initial terms</a>.
%H A255405 Wikipedia, <a href="http://en.wikipedia.org/wiki/Squaring_the_circle">Squaring the circle</a>.
%F A255405 a(n) = floor((2/sqrt(Pi))^n).
%t A255405 Table[Floor[(2/Sqrt[Pi])^n], {n,0,50}] (* _G. C. Greubel_, Jan 09 2017 *)
%o A255405 (PARI){for(n=1,100,a=floor(2^n/sqrt(Pi)^n);print1(a,", "))}
%Y A255405 Cf. A002161, A255162, A255163.
%K A255405 nonn
%O A255405 0,6
%A A255405 _Kival Ngaokrajang_, Feb 22 2015