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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

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

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Last modified January 19 21:35 EST 2018. Contains 297938 sequences.