Number of ways to place 5 nonattacking semi-queens on an n X n board.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =23a(5) =1104a(6) =16945a(7) =141696a(8) =810746a(9) =3568352a(10) =12948318a(11) =40514560a(12) =112720393a(13) =285073712a(14) =666143975a(15) =1456288512a(16) =3007576740a(17) =5913372864a(18) =11138305068a(19) =20202100224a(20) =35433809451a(21) =60316600080a(22) =99947225741a(23) =161638967424a(24) =255701773822a(25) =396439174560a(26) =603407582570