Number of ways to reciprocally link elements of an n X 2 array either to themselves or to exactly two king-move neighbors.

A220590

Number of ways to reciprocally link elements of an n X 2 array either to themselves or to exactly two king-move neighbors.

Terms

    a(0) =1a(1) =8a(2) =33a(3) =155a(4) =710a(5) =3265a(6) =15009a(7) =68992a(8) =317149a(9) =1457879a(10) =6701646a(11) =30806405a(12) =141612197a(13) =650968960a(14) =2992401777a(15) =13755599635a(16) =63232324870a(17) =290669037689

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