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 A325741 #4 Jun 03 2019 19:48:12
%S A325741 1,1,-2,4,-8,16,-32,64,-127,246,-456,792,-1254,1716,-1716,1,6418,
%T A325741 -24156,67080,-162924,364608,-767976,1535953,-2922702,5273624,
%U A325741 -8934120,13904190,-18874260,18874260,1,-71705866,272491892,-763189064,1865459352,-4190875872
%N A325741 First term of n-th difference sequence of (floor(Pi*k/2)), k >= 0.
%H A325741 Clark Kimberling, <a href="/A325741/b325741.txt">Table of n, a(n) for n = 1..200</a>
%t A325741 Table[First[Differences[Table[Floor[(Pi/2)*n], {n, 0, 50}], n]], {n, 1, 50}]
%Y A325741 Cf. A019669, A325664.
%K A325741 easy,sign
%O A325741 1,3
%A A325741 _Clark Kimberling_, May 23 2019