Number of ways to place 5n nonattacking kings on a vertical cylinder 10 X 2n.

Terms

a(0) =64a(1) =732a(2) =4392a(3) =18890a(4) =66532a(5) =205628a(6) =580664a(7) =1536814a(8) =3877300a(9) =9434784a(10) =22327496a(11) =51698178a(12) =117645348a(13) =263992580a(14) =585640568a(15) =1286898262a(16) =2805399156a(17) =6074441896a(18) =13076687560a(19) =28009586346a(20) =59732295204a(21) =126891641612a(22) =268638308152a(23) =566987715710