|
|
A201977
|
|
Number of nX4 0..3 arrays with rows and columns lexicographically nondecreasing read forwards and nonincreasing read backwards
|
|
1
|
|
|
4, 131, 9260, 408599, 8002304, 91893727, 729771318, 4412536785, 21616887220, 89573637672, 323882961806, 1046082959963, 3072688515840, 8324694513560, 21037789421604, 50045713319142, 112903666194660, 243057004503527
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = (1/800296713216000)*n^18 + (1/279189504000)*n^17 + (95419/31384184832000)*n^16 + (61393/58118860800)*n^15 + (13474067/89159616000)*n^14 + (1944881051/249080832000)*n^13 + (287748203459/3621252096000)*n^12 - (9381832307/5748019200)*n^11 + (565158095051/109734912000)*n^10 + (1007220012059/8128512000)*n^9 - (4235093372549201/2414168064000)*n^8 + (1553448377549/136857600)*n^7 - (503383886122557787/11769069312000)*n^6 + (655941897398819/7185024000)*n^5 - (4125496035344653/59439744000)*n^4 - (45705619838101/302702400)*n^3 + (7044605010470827/15437822400)*n^2 - (1427735531371/3063060)*n + 171950
|
|
EXAMPLE
|
Some solutions for n=3
..0..0..3..3....0..2..3..3....0..0..0..3....0..1..2..3....1..3..3..3
..1..3..0..2....2..0..0..1....1..1..2..1....1..3..1..0....3..0..0..2
..3..2..2..1....3..3..1..0....3..3..1..1....2..0..0..0....3..2..2..0
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|