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 A341254 #5 Feb 16 2021 01:08:38
%S A341254 4,8,12,16,21,25,29,33,40,44,48,52,57,61,65,69,76,80,84,88,93,97,101,
%T A341254 105,110,116,120,124,129,133,137,141,146,152,156,160,165,169,173,177,
%U A341254 182,186,192,196,201,205,209,213,218,222,228,232,237,241,245,249
%N A341254 a(n) = floor(r*floor(r*n)), where r = (2 + sqrt(5))/2.
%C A341254 Conjecture: 1/4 < n*r^2 - a(n) < 3 for n >= 1.
%t A341254 z = 50; r = GoldenRatio + 1/2; f[x_] := Floor[r*Floor[r*x]];
%t A341254 Table[f[n], {n, 1, 120} ] (* A341254 *)
%Y A341254 Cf. A341255.
%K A341254 nonn,easy
%O A341254 1,1
%A A341254 _Clark Kimberling_, Feb 13 2021