1/5 the number of n X 2 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

A185818

1/5 the number of n X 2 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

Terms

    a(0) =1a(1) =9a(2) =76a(3) =656a(4) =5680a(5) =49248a(6) =426928a(7) =3701360a(8) =32089696a(9) =278208816a(10) =2411993584a(11) =20911320416a(12) =181295389360

External references