1/3 the number of n X 2 0..2 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

A185552

1/3 the number of n X 2 0..2 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

Terms

    a(0) =1a(1) =5a(2) =26a(3) =120a(4) =576a(5) =2768a(6) =13256a(7) =63544a(8) =304608a(9) =1460072a(10) =6998680a(11) =33547360a(12) =160805064a(13) =770799288a(14) =3694731616a(15) =17710240936a(16) =84891859544a(17) =406918677600

External references