Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal or antidiagonal neighbors.

A220628

Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly two horizontal or antidiagonal neighbors.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =37a(4) =1481a(5) =183961a(6) =72097810a(7) =91163971015

External references