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

Terms

a(0) =0a(1) =0a(2) =6a(3) =405a(4) =5024a(5) =31320a(6) =133544a(7) =446421a(8) =1258590a(9) =3126724a(10) =7042930a(11) =14669709a(12) =28658436a(13) =53069000a(14) =93909924a(15) =159819965a(16) =262913874a(17) =419816676a(18) =652912510a(19) =991835749a(20) =1475233800a(21) =2152832664a(22) =3087838016a(23) =4359706245a(24) =6067321574a(25) =8332617060a(26) =11304678954