A186005 - OEIS

%I #16 Jul 25 2017 02:28:16

%S 1,3,2,4,6,5,7,8,12,11,9,13,15,22,21,10,16,23,26,37,36,14,18,27,38,42,

%T 58,57,17,24,30,43,59,64,86,85,19,28,39,47,65,87,93,122,121,20,31,44,

%U 60,70,94,123,130,167,166,25,33,48,66,88,100,131,168,176,222,221,29,40,51,71,95,124,138,177,223,232,288,287

%N Distance array associated with ordering A057557 of N X N X N by antidiagonals (distances to xy plane).

%C Let n=n(i,j,k) be the position of (i,j,k) in the lexicographic ordering A057557 of N X N X N, where N={1,2,3,...}. Row h of A186005 lists those n for which k=n, the distance from (i,j,k) to the xy-plane. Every positive integer occurs exactly once in the array, so that as a sequence, A186005 is a permutation of the positive integers.

%H G. C. Greubel, <a href="/A186005/b186005.txt">Table of n, a(n) for the first 50 rows, flattened</a>

%e T(2,2)=6, the position of (1,2,2) in the ordering

%e (1,1,1) < (1,1,2) < (1,2,1) < (2,1,1) < (1,1,3) < (1,2,2) < (1,3,1) < ...

%e Northwest corner:

%e    1,  3,  4,  7,  9, 10

%e    2,  6,  8, 13, 16, 18

%e    5, 12, 15, 23, 27, 30

%e   11, 22, 26, 38, 43, 47

%e   21, 37, 42, 59, 65, 70

%t lexicographicLattice[{dim_,maxHeight_}]:=Flatten[Array[Sort@Flatten[(Permutations[#1]&)/@IntegerPartitions[#1+dim-1,{dim}],1]&,maxHeight],1];

%t lexicographicLatticeHeightArray[{dim_,maxHeight_,axis_}]:=Array[Flatten@Position[Map[#[[axis]]&,lexicographicLattice[{dim,maxHeight}]],#]&,maxHeight];

%t llha=lexicographicLatticeHeightArray[{3,12,3}];

%t ordering=lexicographicLattice[{2,Length[llha]}];

%t llha[[#1,#2]]&@@#1&/@ordering

%t (* _Peter J. C. Moses_, Feb 15 2011 *)

%Y Cf. A057557, A186003, A186004.

%K nonn,tabl

%O 1,2

%A _Clark Kimberling_, Feb 10 2011