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 A206903 #11 Mar 30 2012 18:58:12
%S A206903 1,3,4,6,7,10,12,13,15,16,19,20,22,24,25,28,29,31,32,34,37,38,40,41,
%T A206903 43,46,47,49,50,52,53,56,58,59,61,62,65,66,68,70,71,74,75,77,78,80,83,
%U A206903 84,86,87,89,92,93,95,96,98,99,102,104,105,107,108,111,112,114
%N A206903 n+[ns/r]+[nt/r], where []=floor, r=3, s=sqrt(3), t=1/s.
%C A206903 The sequences A206903, A206904, A206905 partition the positive integers. To generate them, jointly rank the sets {n/3}, {n/sqrt(3)}, {n*sqrt(3)} for n>=1. The positions of n/3 in the joint ranking form A206903, and likewise for the other sequences.
%t A206903 r = 3; s = Sqrt[3]; t = 1/s;
%t A206903 a[n_] := n + Floor[n*s/r] + Floor[n*t/r];
%t A206903 b[n_] := n + Floor[n*r/s] + Floor[n*t/s];
%t A206903 c[n_] := n + Floor[n*r/t] + Floor[n*s/t];
%t A206903 Table[a[n], {n, 1, 70}] (* A206903 *)
%t A206903 Table[b[n], {n, 1, 70}] (* A206904 *)
%t A206903 Table[c[n], {n, 1, 70}] (* A206905 *)
%Y A206903 Cf. A206904, A206905.
%K A206903 nonn
%O A206903 1,2
%A A206903 _Clark Kimberling_, Feb 13 2012