Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two king-move neighbors, without 3-loops.

A220646

Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two king-move neighbors, without 3-loops.

Terms

    a(0) =1a(1) =4a(2) =333a(3) =192413a(4) =1233993907

External references