

A191442


Dispersion of ([n*sqrt(3)+1/2]), where [ ]=floor, by antidiagonals.


4



1, 2, 4, 3, 7, 6, 5, 12, 10, 8, 9, 21, 17, 14, 11, 16, 36, 29, 24, 19, 13, 28, 62, 50, 42, 33, 23, 15, 48, 107, 87, 73, 57, 40, 26, 18, 83, 185, 151, 126, 99, 69, 45, 31, 20, 144, 320, 262, 218, 171, 120, 78, 54, 35, 22, 249, 554, 454, 378, 296, 208, 135, 94
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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 nth 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: A191426A191455.


LINKS

Table of n, a(n) for n=1..63.


EXAMPLE

Northwest corner:
1....2....3....5...9
4....7....12...21..36
6....10...17...29..50
8....14...24...42..73
11...19...33...57..99


MATHEMATICA

(* Program generates the dispersion array T of increasing sequence f[n] *)
r=40; r1=12; c=40; c1=12; x = Sqr[3];
f[n_] := Floor[n*x+1/2] (* 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}]]
(* A191442 array *)
Flatten[Table[t[k, n  k + 1], {n, 1, c1}, {k, 1, n}]] (* A191442 sequence *)
(* Program by Peter J. C. Moses, Jun 01 2011 *)


CROSSREFS

Cf. A114537, A035513, A035506.
Sequence in context: A199535 A064274 A035513 * A191738 A218602 A114537
Adjacent sequences: A191439 A191440 A191441 * A191443 A191444 A191445


KEYWORD

nonn,tabl


AUTHOR

Clark Kimberling, Jun 04 2011


STATUS

approved



