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 A194838 #8 Mar 30 2012 18:57:44 %S A194838 1,2,1,3,2,1,3,2,1,4,3,2,5,1,4,3,6,2,5,1,4,7,3,6,2,5,1,4,7,3,6,2,5,1, %T A194838 8,4,7,3,6,2,9,5,1,8,4,7,3,10,6,2,9,5,1,8,4,11,7,3,10,6,2,9,5,1,8,4, %U A194838 11,7,3,10,6,2,9,5,1,12,8,4,11,7,3,10,6,2,13,9,5,1,12,8,4,11,7,3 %N A194838 Triangular array (and fractal sequence): row n is the permutation of (1,2,...,n) obtained from the increasing ordering of fractional parts {r}, {2r}, ..., {nr}, where r=sqrt(3). %C A194838 See A194832 for a general discussion. %e A194838 First nine rows: %e A194838 1 %e A194838 2 1 %e A194838 3 2 1 %e A194838 3 2 1 4 %e A194838 3 2 5 1 4 %e A194838 3 6 2 5 1 4 %e A194838 7 3 6 2 5 1 4 %e A194838 7 3 6 2 5 1 8 4 %e A194838 7 3 6 2 9 5 1 8 4 %t A194838 r = Sqrt[3]; %t A194838 t[n_] := Table[FractionalPart[k*r], {k, 1, n}]; %t A194838 f = Flatten[Table[Flatten[(Position[t[n], #1] &) /@ Sort[t[n], Less]], {n, 1, 20}]] (* A194838 *) %t A194838 TableForm[Table[Flatten[(Position[t[n], #1] &) /@ Sort[t[n], Less]], {n, 1, 15}]] %t A194838 row[n_] := Position[f, n]; %t A194838 u = TableForm[Table[row[n], {n, 1, 20}]] %t A194838 g[n_, k_] := Part[row[n], k]; %t A194838 p = Flatten[Table[g[k, n - k + 1], {n, 1, 13}, %t A194838 {k, 1, n}]] (* A194839 *) %t A194838 q[n_] := Position[p, n]; Flatten[ %t A194838 Table[q[n], {n, 1, 80}]] (* A194840 *) %Y A194838 Cf. A194832, A194839, A194840. %K A194838 nonn,tabl %O A194838 1,2 %A A194838 _Clark Kimberling_, Sep 03 2011