A186168 T(n,k)=1/4 the number of nXk 0..3 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

0, 1, 1, 1, 7, 1, 4, 48, 48, 4, 7, 321, 702, 321, 7, 19, 2175, 14364, 14364, 2175, 19, 40, 14748, 253341, 751266, 253341, 14748, 40, 97, 99933, 4762206, 37402872, 37402872, 4762206, 99933, 97, 217, 677283, 87054174, 1899336597, 5033988714, 1899336597

Offset: 1

Author

R. H. Hardin Feb 13 2011

Keywords

• nonn
• tabl

Comments

Table starts

...0........1............1...............4.................7.................19

...1........7...........48.............321..............2175..............14748

...1.......48..........702...........14364............253341............4762206

...4......321........14364..........751266..........37402872.........1899336597

...7.....2175.......253341........37402872........5033988714.......704281652979

..19....14748......4762206......1899336597......704281652979....268995986029278

..40....99933.....87054174.....95752776009....96951738076992.101554003879403823

..97...677283...1610684397...4840082975532.13435825601048421

.217..4590168..29645381115.244420512852030

.508.31108893.546876640548

Examples

			Some solutions for 5X4 with a(1,1)=0
..0..0..1..0....0..0..1..1....0..0..1..1....0..0..1..0....0..0..1..1
..0..0..1..0....0..0..3..2....0..0..2..2....0..0..1..0....0..0..2..1
..1..1..3..3....1..1..3..2....1..1..0..0....1..1..0..0....1..1..2..2
..0..0..3..3....0..1..3..2....1..3..3..0....1..1..2..1....2..2..1..0
..1..1..0..0....0..0..0..0....0..0..2..2....0..0..2..1....3..3..1..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..84

Crossrefs

Column 1 is A006130(n-2)