a(n) = (-1)^n*(n^8 + 4*n^7 - 14*n^5 + 28*n^3 - 17*n)/2.

Terms

a(0) =0a(1) =-1a(2) =255a(3) =-6306a(4) =59230a(5) =-331395a(6) =1348221a(7) =-4416580a(8) =12360636a(9) =-30686085a(10) =69313915a(11) =-145044966a(12) =284936730a(13) =-530793991a(14) =944995065a(15) =-1617895560a(16) =2677071736a(17) =-4298685705a(18) =6721274871a(19) =-10262288170a(20) =15337711830a(21) =-22485147531a(22) =32390726005a(23) =-45920259276a(24) =64155054900a(25) =-88432835725