A223928 Number of n X 3 0..2 arrays with rows, columns and antidiagonals unimodal and diagonals nondecreasing.

22, 218, 1116, 4498, 15791, 49646, 142177, 375777, 926559, 2150622, 4734429, 9947574, 20054339, 38965176, 73242344, 133617438, 237234842, 410906947, 695757399, 1153741182, 1876668923, 2998531806, 4712127751, 7291234403

Offset

1,1

Comments

Column 3 of A223933.

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 + (1387/43545600)*n^10 + (577/1451520)*n^9 + (2717/414720)*n^8 + (10553/483840)*n^7 + (13338121/43545600)*n^6 + (19135/32256)*n^5 + (9514387/2177280)*n^4 + (1557389/362880)*n^3 + (1225691/118800)*n^2 + (1887533/27720)*n - 124 for n>3.

Example

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

Crossrefs

Cf. A223933.

Sequence in context: A126543 A232019 A224330 * A224052 A224305 A224369

Adjacent sequences: A223925 A223926 A223927 * A223929 A223930 A223931

Keyword

nonn

Author

R. H. Hardin, Mar 29 2013

Status

approved