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A182798
Number of 4-colorings of the n X n X n triangular grid.
12
4, 24, 192, 2112, 32640, 718080, 22665216, 1031276544, 67849629696, 6468240187392, 894839431299072, 179851071814434816, 52561241074964496384, 22351071118387029737472, 13837189739906569661841408
OFFSET
1,1
COMMENTS
The n X n X n triangular grid has n rows with k vertices in row k. 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(n) vertices and 3*A000217(n-1) edges altogether.
FORMULA
a(n) = 4 * A153467(n).
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Dec 02 2010
EXTENSIONS
a(15) from Alois P. Heinz, Mar 11 2016
STATUS
approved