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 A300077 #15 Jan 12 2022 17:06:35
%S A300077 1,15,157,1570,15707,157079,1570796,15707963,157079632,1570796326,
%T A300077 15707963267,157079632679,1570796326794,15707963267948,
%U A300077 157079632679489,1570796326794896,15707963267948966,157079632679489661,1570796326794896619,15707963267948966192
%N A300077 Decimal expansion of Pi/2 truncated to n places.
%F A300077 a(n) = floor((1/2)*Pi*10^n), Pi = 3.14159265...
%p A300077 seq(floor(1/2*Pi*10^n),n=0..19);
%t A300077 Array[Floor[10^#*Pi/2] &, 20, 0] (* _Michael De Vlieger_, Feb 25 2018 *)
%t A300077 Module[{nn=30,pi2},pi2=RealDigits[Pi/2,10,nn][[1]];Table[FromDigits[ Take[ pi2,n]],{n,nn}]] (* _Harvey P. Dale_, Jan 12 2022 *)
%Y A300077 Cf. A011545, A019669.
%K A300077 nonn,base,easy,less
%O A300077 1,2
%A A300077 _Martin Renner_, Feb 24 2018