A224045 Number of nX3 0..3 arrays with rows and columns unimodal and antidiagonals nondecreasing.
50, 984, 9731, 67585, 376734, 1801402, 7655477, 29502561, 104437965, 342818189, 1051490221, 3033475639, 8279003183, 21484969347, 53256520053, 126598758740, 289630093258, 639706047860, 1367894672765, 2838837855851, 5730717831654
Offset: 1
Keywords
Examples
Some solutions for n=3 ..2..0..0....1..1..0....0..1..0....3..3..0....0..0..2....0..1..0....0..0..0 ..3..1..0....1..1..3....3..3..0....3..1..1....0..2..0....1..2..2....0..1..0 ..1..3..0....1..3..1....3..0..0....2..1..1....2..3..0....2..2..2....2..2..3
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = (1/3629463552000)*n^18 + (7/403273728000)*n^17 + (667/951035904000)*n^16 + (3253/174356582400)*n^15 + (1895917/5230697472000)*n^14 + (1319281/249080832000)*n^13 + (509321/8211456000)*n^12 + (100859/174182400)*n^11 + (332201027/73156608000)*n^10 + (728354747/24385536000)*n^9 + (143150448337/804722688000)*n^8 + (121759327/136857600)*n^7 + (2559704983/808704000)*n^6 + (221471493559/31135104000)*n^5 + (346834471679/24216192000)*n^4 + (1741800289/181621440)*n^3 + (25437920323/1715313600)*n^2 + (1383692/69615)*n - 32 for n>1
Comments