T(n,k) = Number of n X k 0..1 arrays with every one equal to some NW, E or S neighbor.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =4a(5) =1a(6) =1a(7) =14a(8) =14a(9) =1a(10) =1a(11) =40a(12) =93a(13) =40a(14) =1a(15) =1a(16) =116a(17) =494a(18) =494a(19) =116a(20) =1a(21) =1a(22) =344a(23) =2801a(24) =4892a(25) =2801a(26) =344a(27) =1a(28) =1a(29) =1016