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

Terms

a(0) =0a(1) =0a(2) =38a(3) =340a(4) =1630a(5) =5552a(6) =15210a(7) =35828a(8) =75530a(9) =146240a(10) =264702a(11) =453620a(12) =742918a(13) =1171120a(14) =1786850a(15) =2650452a(16) =3835730a(17) =5431808a(18) =7545110a(19) =10301460a(20) =13848302a(21) =18357040a(22) =24025498a(23) =31080500a(24) =39780570a(25) =50418752a(26) =63325550a(27) =78871988a(28) =97472790a(29) =119589680