Number of ways to place 3 nonattacking bishops on an n X n board.

Terms

a(0) =0a(1) =0a(2) =26a(3) =232a(4) =1124a(5) =3896a(6) =10894a(7) =26192a(8) =56296a(9) =110960a(10) =204130a(11) =355000a(12) =589196a(13) =940072a(14) =1450134a(15) =2172576a(16) =3172944a(17) =4530912a(18) =6342186a(19) =8720520a(20) =11799860a(21) =15736600a(22) =20711966a(23) =26934512a(24) =34642744a(25) =44107856a(26) =55636594a(27) =69574232