Number of 3-turn bishop's tours on an n X n board summed over all starting positions.

Terms

a(0) =0a(1) =0a(2) =28a(3) =152a(4) =488a(5) =1192a(6) =2468a(7) =4560a(8) =7760a(9) =12400a(10) =18860a(11) =27560a(12) =38968a(13) =53592a(14) =71988a(15) =94752a(16) =122528a(17) =156000a(18) =195900a(19) =243000a(20) =298120a(21) =362120a(22) =435908a(23) =520432a(24) =616688a(25) =725712a(26) =848588a(27) =986440a(28) =1140440a(29) =1311800