OFFSET
1,6
COMMENTS
Length of n-th row is A004396(n) + 1, for 1 <= n <= 21, where A004396(n) is the maximal number of points that can be placed under the condition mentioned above.
Rotations and reflections of placements are not counted. If they are to be counted, see A193986.
In terms or triangular chess: Number of nonequivalent ways (mod D_3) to arrange k nonattacking rooks on an n X n X n board, k>=0, n>=1.
LINKS
Heinrich Ludwig, Table of n, a(n) for n = 1..175
EXAMPLE
The table begins with T(1,0), T(1,1);
1, 1;
1, 1;
1, 2, 1;
1, 3, 3, 1;
1, 4, 9, 5;
1, 5, 19, 23, 3;
1, 7, 38, 82, 40, 1;
1, 8, 66, 230, 242, 45;
1, 10, 110, 560, 1038, 533, 29;
...
CROSSREFS
KEYWORD
nonn,tabf
AUTHOR
Heinrich Ludwig, Mar 10 2017
STATUS
approved