Number of ways to reciprocally link elements of an 4 X n array either to themselves or to exactly two horizontal or antidiagonal neighbors.

A220634

Number of ways to reciprocally link elements of an 4 X n array either to themselves or to exactly two horizontal or antidiagonal neighbors.

Terms

    a(0) =1a(1) =1a(2) =5a(3) =37a(4) =257a(5) =1665a(6) =10695a(7) =68637a(8) =440509a(9) =2827377a(10) =18148003a(11) =116487861a(12) =747713321a(13) =4799439985a(14) =30806785967a(15) =197743565181

External references