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Number of nX2 0..3 arrays with rows and columns in nondecreasing order
1

%I #6 Mar 31 2012 12:35:56

%S 10,86,561,2861,12068,43947,142376,419213,1139569,2894178,6931366,

%T 15770131,34291532,71619470,144269412,281284873,532422712,980922994,

%U 1763049635,3097467201,5328692624,8990408705,14896447100,24269860485

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

%C Column 2 of A184129

%H R. H. Hardin, <a href="/A184122/b184122.txt">Table of n, a(n) for n = 1..200</a>

%F 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)

%e Some solutions for 3X2

%e ..0..1....2..2....0..1....0..2....0..1....2..3....0..3....0..2....1..2....1..2

%e ..0..1....2..2....2..0....1..3....3..0....2..3....2..3....1..2....2..0....1..2

%e ..3..3....2..3....2..2....2..2....3..1....3..1....2..3....2..1....2..3....3..0

%K nonn

%O 1,1

%A _R. H. Hardin_ Jan 09 2011