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
Keywords
Examples
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
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
Comments