A224052 Number of nX3 0..2 arrays with rows and columns unimodal and antidiagonals nondecreasing

22, 218, 1232, 5219, 18502, 57911, 164781, 433762, 1068664, 2485274, 5492414, 11598655, 23514508, 45950300, 86850332, 159256653, 284063565, 494009870, 839363352, 1395884951, 2275822878, 3642884361, 5732370123, 8877939920

Offset

1,1

Comments

Column 3 of A224057

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 + (751/1451520)*n^9 + (3247/580608)*n^8 + (18607/483840)*n^7 + (11286841/43545600)*n^6 + (1893037/1451520)*n^5 + (2032151/435456)*n^4 + (1618571/362880)*n^3 + (7125527/831600)*n^2 + (241067/27720)*n - 9 for n>1

Example

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

Crossrefs

Sequence in context: A232019 A224330 A223928 * A224305 A224369 A331882

Adjacent sequences: A224049 A224050 A224051 * A224053 A224054 A224055

Keyword

nonn

Author

R. H. Hardin Mar 30 2013

Status

approved