A224311 Number of 3Xn 0..2 arrays with diagonals and rows unimodal and antidiagonals nondecreasing

27, 324, 1586, 5996, 20214, 61953, 174378, 454832, 1108958, 2547780, 5554847, 11564081, 23107746, 44519456, 83011127, 150287312, 264917825, 455762696, 766835415, 1264104630, 2044874898, 3250558135, 5083853932, 7831604260

Offset

1,1

Comments

Row 3 of A224310

Links

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

Formula

Empirical: a(n) = (1/19160064)*n^12 + (1/1064448)*n^11 + (1507/43545600)*n^10 + (73/161280)*n^9 + (23603/2903040)*n^8 + (111/3584)*n^7 + (13023121/43545600)*n^6 + (130093/96768)*n^5 + (5619469/2177280)*n^4 + (54895/2688)*n^3 - (11456441/1663200)*n^2 + (205131/1540)*n - 196 for n>3

Example

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

Crossrefs

Sequence in context: A061181 A231911 A182130 * A224375 A010832 A022719

Adjacent sequences: A224308 A224309 A224310 * A224312 A224313 A224314

Keyword

nonn

Author

R. H. Hardin Apr 03 2013

Status

approved