Number of ways to reciprocally link elements of an nX4 array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors.

A220684

Number of ways to reciprocally link elements of an nX4 array either to themselves or to exactly two horizontal, vertical or antidiagonal neighbors.

Terms

    a(0) =1a(1) =37a(2) =745a(3) =15452a(4) =312603a(5) =6349886a(6) =128995678a(7) =2620320833a(8) =53226950200

External references