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 A325667 #12 Feb 20 2022 08:14:40
%S A325667 -2,0,0,1,-4,10,-20,36,-64,120,-240,496,-1024,2080,-4159,8240,-16248,
%T A325667 31824,-61403,115292,-207670,352716,-550430,748144,-748144,0,2848366,
%U A325667 -10897032,30955332,-77558759,181129040,-404458736,875889376,-1855921143,3870685664
%N A325667 First term of n-th difference sequence of (floor(k*r)), r = -sqrt(3), k >= 0.
%H A325667 Clark Kimberling, <a href="/A325667/b325667.txt">Table of n, a(n) for n = 1..200</a>
%t A325667 Table[First[Differences[Table[Floor[-Sqrt[3]*n], {n, 0, 50}], n]], {n, 1, 50}]
%Y A325667 Cf. A325664, A325666.
%K A325667 easy,sign
%O A325667 1,1
%A A325667 _Clark Kimberling_, May 13 2019