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

A220721

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

Terms

    a(0) =1a(1) =21a(2) =230a(3) =2586a(4) =29310a(5) =331589a(6) =3751888a(7) =42452438a(8) =480346122a(9) =5435081884a(10) =61497557384a(11) =695840407309

External references