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 A325665 #10 May 22 2019 22:57:41
%S A325665 -2,1,-2,4,-8,16,-31,56,-91,126,-126,1,449,-1624,4249,-9499,18998,
%T A325665 -34356,55453,-75734,70889,26334,-379050,1352079,-3713651,9000226,
%U A325665 -20136807,42409969,-84819938,161567266,-292710631,501416816,-801992971,1167081366,-1453179126
%N A325665 First term of n-th difference sequence of (floor(k*r)), r = -sqrt(2), k >= 0.
%H A325665 Clark Kimberling, <a href="/A325665/b325665.txt">Table of n, a(n) for n = 1..200</a>
%t A325665 Table[First[Differences[Table[Floor[-Sqrt[2]*n], {n, 0, 50}], n]], {n, 1, 50}]
%Y A325665 Cf. A001951, A325664.
%K A325665 easy,sign
%O A325665 1,1
%A A325665 _Clark Kimberling_, May 12 2019