Number of ways to place 2n nonattacking kings on a 4 X 2n chessboard.

A061593

Number of ways to place 2n nonattacking kings on a 4 X 2n chessboard.

Terms

    a(0) =12a(1) =79a(2) =408a(3) =1847a(4) =7698a(5) =30319a(6) =114606a(7) =419933a(8) =1501674a(9) =5266069a(10) =18174084a(11) =61892669a(12) =208424880a(13) =695179339a(14) =2299608732a(15) =7552444115a(16) =24648046806a(17) =79994460139a(18) =258339007890a(19) =830619734681

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