Number of ways to place 4 nonattacking queens on an n X n toroidal board.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =50a(5) =288a(6) =2450a(7) =16384a(8) =62208a(9) =233600a(10) =638880a(11) =1755072a(12) =3901534a(13) =8772176a(14) =17051850a(15) =33507328a(16) =59175640a(17) =105557904a(18) =173570244a(19) =287904000a(20) =447885774a(21) =702042000a(22) =1044894554a(23) =1565385984a(24) =2247132500a(25) =3244194304a(26) =4519015596