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 A325738 #4 Jun 03 2019 19:47:53
%S A325738 1,0,1,-3,6,-9,9,0,-27,81,-162,243,-243,1,714,-2067,3695,-3519,-4896,
%T A325738 37621,-129999,352716,-836111,1802901,-3605802,6760781,-11961081,
%U A325738 20058301,-32017846,48916881,-72174561,104394081,-151428366,226511451,-357639591,600805296
%N A325738 First term of n-th difference sequence of (floor(e*k/2)), k >= 0.
%H A325738 Clark Kimberling, <a href="/A325738/b325738.txt">Table of n, a(n) for n = 1..200</a>
%t A325738 Table[First[Differences[Table[Floor[(E/2)*n], {n, 0, 50}], n]], {n, 1, 50}]
%Y A325738 Cf. A325664.
%K A325738 easy,sign
%O A325738 1,4
%A A325738 _Clark Kimberling_, May 23 2019