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 A072398 #31 Jul 17 2023 06:00:55
%S A072398 3,22,22,355,355,312689,1146408,5419351,245850922,2549491779,
%T A072398 21053343141,21053343141,1783366216531,8958937768937,139755218526789,
%U A072398 428224593349304,30246273033735921,66627445592888887
%N A072398 Numerator of best approximation to Pi with denominator <= 10^n.
%H A072398 Daniel Mondot, <a href="/A072398/b072398.txt">Table of n, a(n) for n = 0..999</a>
%e A072398 A072398(5) = 312689 because A072398(5)/A072399(5) = 312689/99532 is the best rational approximation to Pi with positive denominator <= 10^5 = 100000. This approximation is accurate to 0.00000000092766%.
%t A072398 nmax = 17; cv = Convergents[Pi, 2*nmax] // Reverse; a[n_] := Select[cv, Denominator[#] <= 10^n &, 1] // Numerator // First; Table[a[n], {n, 0, nmax}] (* _Jean-François Alcover_, Jan 04 2013 *)
%o A072398 (PARI) for(n=0,40,print1(numerator(bestappr(Pi,10^n)),",")) \\ Finds these approximations very quickly.
%Y A072398 Cf. A072399 (denominators), A000796 (Pi), A068089, A002485/A002486.
%K A072398 easy,frac,nice,nonn
%O A072398 0,1
%A A072398 _Rick L. Shepherd_, Jun 15 2002