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 A325731 #12 Jul 20 2019 19:42:53
%S A325731 0,1,-1,1,-1,0,5,-20,55,-125,250,-450,725,-1000,1000,1,-3642,13278,
%T A325731 -35344,81720,-174098,352716,-694904,1355322,-2652200,5245956,
%U A325731 -10491911,21097440,-42262518,83482620,-161013975,300338820,-536165400,903201960,-1401448500
%N A325731 First term of n-th difference sequence of (floor(k*r)), r = sqrt(2/3), k >= 0.
%H A325731 Clark Kimberling, <a href="/A325731/b325731.txt">Table of n, a(n) for n = 1..200</a>
%t A325731 Table[First[Differences[Table[Floor[Sqrt[2/3]*n], {n, 0, 50}], n]], {n, 1, 50}]
%Y A325731 Cf. A325664. Inverse binomial transform of A171974.
%K A325731 easy,sign
%O A325731 1,7
%A A325731 _Clark Kimberling_, May 20 2019