A201981 - OEIS

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A201981

T(n,k)=Number of nXk 0..3 arrays with rows and columns lexicographically nondecreasing read forwards and nonincreasing read backwards

4, 4, 4, 4, 30, 4, 4, 72, 72, 4, 4, 131, 1372, 131, 4, 4, 208, 9260, 9260, 208, 4, 4, 304, 38112, 408599, 38112, 304, 4, 4, 420, 117744, 8002304, 8002304, 117744, 420, 4, 4, 557, 301612, 91893727, 858105364, 91893727, 301612, 557, 4, 4, 716, 676792

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Table starts

.4...4.......4...........4...............4..................4

.4..30......72.........131.............208................304

.4..72....1372........9260...........38112.............117744

.4.131....9260......408599.........8002304...........91893727

.4.208...38112.....8002304.......858105364........48452117136

.4.304..117744....91893727.....48452117136.....13486744809160

.4.420..301612...729771318...1706069013928...2238761872232964

.4.557..676792..4412536785..41801237632858.248685266018356303

.4.716.1375740.21616887220.764295988745248

.4.898.2589832.89573637672

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..97

FORMULA

Empirical: rows (and columns) 2,3,4,5 are polynomials of degree 3,6,18,30

EXAMPLE

Some solutions for n=5 k=3

..1..2..3....1..3..3....0..2..2....1..2..3....0..1..2....0..1..2....0..0..1

..2..0..3....2..1..3....2..1..2....2..0..3....1..0..2....2..1..1....1..3..0

..2..2..2....2..1..3....3..0..1....2..2..2....1..2..1....3..2..0....3..2..0

..3..0..1....3..0..3....3..2..0....3..3..0....2..1..1....3..2..0....3..2..0

..3..3..0....3..3..2....3..2..0....3..3..0....3..2..0....3..2..0....3..2..0

CROSSREFS

Sequence in context: A024727 A024552 A264768 * A309500 A321611 A309756

Adjacent sequences: A201978 A201979 A201980 * A201982 A201983 A201984

KEYWORD

nonn,tabl

AUTHOR

R. H. Hardin Dec 07 2011

STATUS

approved