A191541 Dispersion of (2*floor(n*sqrt(2))), by antidiagonals.

1, 2, 3, 4, 8, 5, 10, 22, 14, 6, 28, 62, 38, 16, 7, 78, 174, 106, 44, 18, 9, 220, 492, 298, 124, 50, 24, 11, 622, 1390, 842, 350, 140, 66, 30, 12, 1758, 3930, 2380, 988, 394, 186, 84, 32, 13, 4972, 11114, 6730, 2794, 1114, 526, 236, 90, 36, 15, 14062, 31434

Offset

1,2

Comments

Background discussion: Suppose that s is an increasing sequence of positive integers, that the complement t of s is infinite, and that t(1)=1. The dispersion of s is the array D whose n-th row is (t(n), s(t(n)), s(s(t(n))), s(s(s(t(n)))), ...). Every positive integer occurs exactly once in D, so that, as a sequence, D is a permutation of the positive integers. The sequence u given by u(n)=(number of the row of D that contains n) is a fractal sequence. Examples:

(1) s=A000040 (the primes), D=A114537, u=A114538.

(2) s=A022343 (without initial 0), D=A035513 (Wythoff array), u=A003603.

(3) s=A007067, D=A035506 (Stolarsky array), u=A133299.

More recent examples of dispersions: A191426-A191455.

Links

Table of n, a(n) for n=1..57.

Example

Northwest corner:
  1...2....4....10...28
  3...8....22...62...174
  5...14...38...106..298
  6...16...44...124..350
  7...18...50...140..394

Mathematica

(* Program generates the dispersion array T of the complement of increasing sequence f[n] *)
r=40; r1=12; c=40; c1=12; f[n_] :=2*Floor[n*Sqrt[2]]   (* complement of column 1 *)
mex[list_] := NestWhile[#1 + 1 &, 1, Union[list][[#1]] <= #1 &, 1, Length[Union[list]]]
rows = {NestList[f, 1, c]};
Do[rows = Append[rows, NestList[f, mex[Flatten[rows]], r]], {r}];
t[i_, j_] := rows[[i, j]];
TableForm[Table[t[i, j], {i, 1, 10}, {j, 1, 10}]]
(* A191541 array *)
Flatten[Table[t[k, n - k + 1], {n, 1, c1}, {k, 1, n}]] (* A191541 sequence *)
(* Program by Peter J. C. Moses, Jun 01 2011 *)

Crossrefs

Cf. A114537, A035513, A035506, A191540.

Sequence in context: A181799 A137623 A358875 * A122398 A329567 A326487

Adjacent sequences: A191538 A191539 A191540 * A191542 A191543 A191544

Keyword

nonn,tabl

Author

Clark Kimberling, Jun 07 2011

Status

approved