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.

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.

Terms

    a(0) =0a(1) =1a(2) =1a(3) =1a(4) =7a(5) =1a(6) =4a(7) =48a(8) =48a(9) =4a(10) =7a(11) =321a(12) =702a(13) =321a(14) =7a(15) =19a(16) =2175a(17) =14364a(18) =14364a(19) =2175a(20) =19a(21) =40a(22) =14748a(23) =253341a(24) =751266a(25) =253341a(26) =14748a(27) =40a(28) =97a(29) =99933

External references