A194048 - OEIS

%I #5 Mar 30 2012 18:57:39

%S 1,5,2,14,6,3,30,15,7,4,55,31,16,8,9,91,56,32,17,18,10,140,92,57,33,

%T 34,19,11,204,141,93,58,59,35,20,12,285,205,142,94,95,60,36,21,13,385,

%U 286,206,143,144,96,61,37,22,23

%N Natural interspersion of A000330, a rectangular array, by antidiagonals.

%C See A194029 for definitions of natural fractal sequence and natural interspersion.  Every positive integer occurs exactly once (and every pair of rows intersperse), so that as a sequence, A194048 is a permutation of the positive integers; its inverse is A194049.

%e Northwest corner:

%e 1...5...14...30...55

%e 2...6...15...31...56

%e 3...7...16...32...57

%e 4...8...17...33...58

%e 9...18..34...59...95

%t Remove["Global`*"];

%t z = 30;

%t c[k_] := k (k + 1) (2 k + 1)/6;

%t c = Table[c[k], {k, 1, z}]  (* A000330 *)

%t f[n_] := If[MemberQ[c, n], 1, 1 + f[n - 1]]

%t f = Table[f[n], {n, 1, 500}]  (* fractal sequence [A064866] *)

%t r[n_] := Flatten[Position[f, n]]

%t t[n_, k_] := r[n][[k]]

%t TableForm[Table[t[n, k], {n, 1, 7}, {k, 1, 7}]]

%t p = Flatten[Table[t[k, n - k + 1], {n, 1, 10}, {k, 1, n}]]  (* A194048 *)

%t q[n_] := Position[p, n]; Flatten[Table[q[n], {n, 1, 70}]] (* A194049 *)

%Y Cf. A194029, A194049.

%K nonn,tabl

%O 1,2

%A _Clark Kimberling_, Aug 13 2011