A224263 Number of 3 X n 0..2 arrays with rows, diagonals and antidiagonals unimodal and columns nondecreasing.

10, 100, 648, 3096, 12032, 40182, 119367, 322885, 808618, 1898050, 4215105, 8921265, 18101023, 35375831, 66857059, 122591129, 218705294, 380533212, 647088610, 1077366434, 1759087854, 2820672704, 4447425227, 6903161705, 10558797550, 15929753130, 23724438995, 34906549843

Offset: 1

Author

R. H. Hardin, Apr 02 2013

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Row 3 of A224262.

Formula

Empirical: a(n) = (1/19160064)*n^12 + (1/1064448)*n^11 + (181/6220800)*n^10 + (557/1451520)*n^9 + (13571/2903040)*n^8 + (3197/96768)*n^7 + (8451841/43545600)*n^6 + (316789/483840)*n^5 + (535159/311040)*n^4 + (151169/72576)*n^3 + (9281749/1663200)*n^2 - (73057/13860)*n + 5.

Extensions

Name corrected by Andrew Howroyd, Mar 18 2025