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 A194857 #5 Mar 30 2012 18:57:44 %S A194857 1,3,2,6,5,4,10,9,8,7,14,13,12,11,15,20,18,17,16,21,19,27,25,23,22,28, %T A194857 26,24,35,33,31,29,36,34,32,30,43,41,39,37,44,42,40,38,45,53,50,48,46, %U A194857 54,51,49,47,55,52,64,61,58,56,65,62,59,57,66,63,60,76,73,70 %N A194857 Rectangular array, by antidiagonals: row n gives the positions of n in the fractal sequence A194856; an interspersion. %C A194857 See A194832 for a general discussion. %e A194857 Northwest corner: %e A194857 1...3...6...10...14...20 %e A194857 2...5...9...13...18...25 %e A194857 4...8...12..17...23...51 %e A194857 7...11..16..22...29...37 %e A194857 15..21..38..36...44...54 %t A194857 r = -Sqrt[5]; %t A194857 t[n_] := Table[FractionalPart[k*r], {k, 1, n}]; %t A194857 f = Flatten[Table[Flatten[(Position[t[n], #1] &) /@ %t A194857 Sort[t[n], Less]], {n, 1, 20}]] (* A194856 *) %t A194857 TableForm[Table[Flatten[(Position[t[n], #1] &) /@ %t A194857 Sort[t[n], Less]], {n, 1, 15}]] %t A194857 row[n_] := Position[f, n]; %t A194857 u = TableForm[Table[row[n], {n, 1, 20}]] %t A194857 g[n_, k_] := Part[row[n], k]; %t A194857 p = Flatten[Table[g[k, n - k + 1], {n, 1, 13}, %t A194857 {k, 1, n}]] (* A194857 *) %t A194857 q[n_] := Position[p, n]; Flatten[Table[q[n], %t A194857 {n, 1, 80}]] (* A194858 *) %Y A194857 Cf. A194856, A194858, A194832. %K A194857 nonn,tabl %O A194857 1,2 %A A194857 _Clark Kimberling_, Sep 04 2011