Number of non-equivalent ways to place 3 non-attacking ferses on an n X n board.

Terms

a(0) =0a(1) =0a(2) =7a(3) =45a(4) =225a(5) =709a(6) =1974a(7) =4524a(8) =9614a(9) =18382a(10) =33425a(11) =56895a(12) =93447a(13) =146715a(14) =224280a(15) =331814a(16) =480844a(17) =679724a(18) =945099a(19) =1288737a(20) =1733725a(21) =2296065a(22) =3006762a(23) =3886960a(24) =4977210a(25) =6304794a(26) =7921589a(27) =9862099a(28) =12191459a(29) =14952567