A201977 Number of nX4 0..3 arrays with rows and columns lexicographically nondecreasing read forwards and nonincreasing read backwards

4, 131, 9260, 408599, 8002304, 91893727, 729771318, 4412536785, 21616887220, 89573637672, 323882961806, 1046082959963, 3072688515840, 8324694513560, 21037789421604, 50045713319142, 112903666194660, 243057004503527

Offset

1,1

Comments

Column 4 of A201981

Links

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

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

Sequence in context: A209012 A003371 A113253 * A291172 A194536 A064227

Adjacent sequences: A201974 A201975 A201976 * A201978 A201979 A201980

Keyword

nonn

Author

R. H. Hardin Dec 07 2011

Status

approved