OFFSET
1,3
COMMENTS
The k X k X k triangular grid has k rows with i vertices in row i. Each vertex is connected to the neighbors in the same row and up to two vertices in each of the neighboring rows. The graph has A000217(k) vertices and 3*A000217(k-1) edges altogether.
The coefficients of the chromatic polynomials for the column sequences are given by the rows of A193283. - Georg Fischer, Jul 31 2023
LINKS
EXAMPLE
Square array A(n,k) begins:
1, 0, 0, 0, 0, 0, ...
2, 0, 0, 0, 0, 0, ...
3, 6, 6, 6, 6, 6, ...
4, 24, 192, 2112, 32640, 718080, ...
5, 60, 1620, 98820, 13638780, 4260983940, ...
6, 120, 7680, 1574400, 1034019840, 2175789895680, ...
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Alois P. Heinz, Dec 02 2010
STATUS
approved