[seqfan] Re: Problem reproducing A019989, A019990, and A019991

[Brad Klee]

RWGs number defs. seem to work for me.

Here is a transcription to Mathematica:

iterate[sets_] := With[{ind = {
     {1, 5, 6}, {2, 6, 4}, {3, 4, 5},
     {4, 3, 2}, {5, 1, 3}, {6, 2, 1}}},
  Union @@ (3 sets[[#]] + {0, -1, 1}) & /@ ind]

data = Union @@ # & /@ Transpose[NestList[iterate,
       Append[Table[{}, 5], {1}], 10][[All, 1 ;; 3]]/2];

TableForm at data[[All, 1 ;; 10]]

As for the encyclopedia entry, it would be
interesting to see an explanation as opposed
to a completely blank entry.

Cheers,

--Brad