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T(n,k)=1/3 the number of nXk 0..2 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors
9

%I #7 Mar 31 2012 12:36:02

%S 0,1,1,1,5,1,3,26,26,3,5,120,224,120,5,11,576,2530,2530,576,11,21,

%T 2768,25496,58458,25496,2768,21,43,13256,269496,1317540,1317540,

%U 269496,13256,43,85,63544,2792166,30132444,64354744,30132444,2792166,63544,85,171

%N T(n,k)=1/3 the number of nXk 0..2 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors

%C Table starts

%C ...0.......1..........1.............3.................5.................11

%C ...1.......5.........26...........120...............576...............2768

%C ...1......26........224..........2530.............25496.............269496

%C ...3.....120.......2530.........58458...........1317540...........30132444

%C ...5.....576......25496.......1317540..........64354744.........3228500154

%C ..11....2768.....269496......30132444........3228500154.......353403366772

%C ..21...13256....2792166.....684657326......160107914496.....38323943289566

%C ..43...63544...29168100...15594228288.....7976049592892...4170998760222200

%C ..85..304608..303674928..354894362166...396657534279472.453352604882802786

%C .171.1460072.3165976954.8078976180614.19739291980979494

%H R. H. Hardin, <a href="/A185559/b185559.txt">Table of n, a(n) for n = 1..111</a>

%e Some solutions for 5X4 with a(1,1)=0

%e ..0..0..0..0....0..0..0..0....0..0..0..1....0..0..0..1....0..0..0..1

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

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

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

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

%Y Column 1 is A001045(n-1)

%K nonn,tabl

%O 1,5

%A _R. H. Hardin_ Jan 31 2011