A224205 Number of 3Xn 0..3 arrays with rows unimodal and antidiagonals nondecreasing

64, 1600, 16060, 108625, 586343, 2734683, 11446096, 43787371, 154644169, 507763502, 1559390798, 4504599056, 12304311893, 31936080080, 79116405604, 187828358540, 428877669532, 944895859570, 2014476071694, 4166609485641

Offset

1,1

Comments

Row 3 of A224204

Links

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

Formula

Empirical: a(n) = (1/3629463552000)*n^18 + (1/44808192000)*n^17 + (10403/10461394944000)*n^16 + (10537/373621248000)*n^15 + (2917237/5230697472000)*n^14 + (6087761/747242496000)*n^13 + (5301533/57480192000)*n^12 + (3437329/4105728000)*n^11 + (464094467/73156608000)*n^10 + (442073521/10450944000)*n^9 + (211531872283/804722688000)*n^8 + (20899761511/14370048000)*n^7 + (120074702257/20756736000)*n^6 + (177621646127/13343616000)*n^5 + (1548685310923/72648576000)*n^4 + (22497639401/1297296000)*n^3 + (9654394423/1715313600)*n^2 + (19245361/1021020)*n - 20

Example

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

Crossrefs

Sequence in context: A282526 A014794 A224282 * A162994 A225981 A232427

Adjacent sequences: A224202 A224203 A224204 * A224206 A224207 A224208

Keyword

nonn

Author

R. H. Hardin Apr 01 2013

Status

approved