T(n,k)=1/5 the number of nXk 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

A185825

T(n,k)=1/5 the number of nXk 0..4 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) =9a(5) =1a(6) =5a(7) =76a(8) =76a(9) =5a(10) =9a(11) =656a(12) =1584a(13) =656a(14) =9a(15) =29a(16) =5680a(17) =49036a(18) =49036a(19) =5680a(20) =29a(21) =65a(22) =49248a(23) =1266624a(24) =4443292a(25) =1266624a(26) =49248a(27) =65a(28) =181a(29) =426928

External references