A184122 Number of nX2 0..3 arrays with rows and columns in nondecreasing order

10, 86, 561, 2861, 12068, 43947, 142376, 419213, 1139569, 2894178, 6931366, 15770131, 34291532, 71619470, 144269412, 281284873, 532422712, 980922994, 1763049635, 3097467201, 5328692624, 8990408705, 14896447100, 24269860485

Offset

1,1

Comments

Column 2 of A184129

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n)=16*a(n-1)-120*a(n-2)+560*a(n-3)-1820*a(n-4)+4368*a(n-5)-8008*a(n-6)+11440*a(n-7)-12870*a(n-8)+11440*a(n-9)-8008*a(n-10)+4368*a(n-11)-1820*a(n-12)+560*a(n-13)-120*a(n-14)+16*a(n-15)-a(n-16) (=polynomial of degree 15)

Example

Some solutions for 3X2
..0..1....2..2....0..1....0..2....0..1....2..3....0..3....0..2....1..2....1..2
..0..1....2..2....2..0....1..3....3..0....2..3....2..3....1..2....2..0....1..2
..3..3....2..3....2..2....2..2....3..1....3..1....2..3....2..1....2..3....3..0

Crossrefs

Sequence in context: A346923 A145146 A252981 * A228123 A163412 A287827

Adjacent sequences: A184119 A184120 A184121 * A184123 A184124 A184125

Keyword

nonn

Author

R. H. Hardin Jan 09 2011

Status

approved