A224052 Number of nX3 0..2 arrays with rows and columns unimodal and antidiagonals nondecreasing.

22, 218, 1232, 5219, 18502, 57911, 164781, 433762, 1068664, 2485274, 5492414, 11598655, 23514508, 45950300, 86850332, 159256653, 284063565, 494009870, 839363352, 1395884951, 2275822878, 3642884361, 5732370123, 8877939920

Offset: 1

Author

R. H. Hardin Mar 30 2013

Keywords

• nonn

Comments

Column 3 of A224057

Examples

			Some solutions for n=3
..0..1..0....2..1..0....1..0..0....0..0..0....1..2..1....2..1..0....0..0..0
..2..1..0....2..2..1....1..1..0....0..0..1....2..2..0....2..0..0....1..2..0
..1..1..2....2..2..1....2..1..1....2..2..2....2..1..0....1..0..0....2..1..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = (1/19160064)*n^12 + (5/3193344)*n^11 + (1627/43545600)*n^10 + (751/1451520)*n^9 + (3247/580608)*n^8 + (18607/483840)*n^7 + (11286841/43545600)*n^6 + (1893037/1451520)*n^5 + (2032151/435456)*n^4 + (1618571/362880)*n^3 + (7125527/831600)*n^2 + (241067/27720)*n - 9 for n>1