A223920 Number of 3Xn 0..2 arrays with rows and antidiagonals unimodal and columns nondecreasing.

10, 100, 666, 3311, 13347, 45988, 140236, 387671, 988447, 2354539, 5291652, 11307388, 23115717, 45438234, 86243127, 158615577, 283521156, 493809754, 839915122, 1397838161, 2280164963, 3651068140, 5746477482, 8900889311

Offset: 1

Author

R. H. Hardin Mar 29 2013

Keywords

• nonn

Comments

Row 3 of A223918

Examples

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

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 + (257/483840)*n^9 + (2309/414720)*n^8 + (19319/483840)*n^7 + (8701321/43545600)*n^6 + (971137/1451520)*n^5 + (3369229/2177280)*n^4 + (294809/120960)*n^3 + (652717/237600)*n^2 + (521/385)*n + 1