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

Terms

a(0) =0a(1) =4a(2) =84a(3) =452a(4) =1772a(5) =5596a(6) =14888a(7) =34640a(8) =72712a(9) =140716a(10) =255036a(11) =437968a(12) =718980a(13) =1136092a(14) =1737376a(15) =2582576a(16) =3744848a(17) =5312620a(18) =7391572a(19) =10106736a(20) =13604716a(21) =18056028a(22) =23657560a(23) =30635152a(24) =39246296a(25) =49782956a(26) =62574508a(27) =77990800