A224276 Number of nX3 0..3 arrays with diagonals and rows unimodal and antidiagonals nondecreasing.

50, 984, 13683, 186516, 2596992, 37128051, 537465766, 7804602744, 113382138975, 1646661944858, 23908590491858, 347099092628781, 5038892410726190, 73149786094975076, 1061918636087967819, 15415943271255819642

Offset: 1

Author

R. H. Hardin Apr 02 2013

Keywords

• nonn

Comments

Column 3 of A224281

Examples

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

Links

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

Formula

Empirical: a(n) = 20*a(n-1) -70*a(n-2) -211*a(n-3) +192*a(n-4) +15174*a(n-5) -36608*a(n-6) -83340*a(n-7) +59774*a(n-8) +2310958*a(n-9) -3620776*a(n-10) -5846720*a(n-11) +390652*a(n-12) [phone]*a(n-13) -70516876*a(n-14) [phone]*a(n-15) +7472696*a(n-16) -557612816*a(n-17) [phone]*a(n-18) -63018416*a(n-19) [phone]*a(n-20) [phone]*a(n-21) -323677440*a(n-22) -14515200*a(n-23) -56540160*a(n-24) -635904000*a(n-25) for n>26