Expansion of bracket function.

Terms

a(0) =1a(1) =-5a(2) =15a(3) =-35a(4) =70a(5) =-125a(6) =200a(7) =-275a(8) =275a(9) =0a(10) =-1000a(11) =3625a(12) =-9500a(13) =21250a(14) =-42500a(15) =76875a(16) =-124375a(17) =171875a(18) =-171875a(19) =0a(20) =621875a(21) =-2250000a(22) =5890625a(23) =-13171875a(24) =26343750a(25) =-47656250a(26) =77109375a(27) =-106562500a(28) =106562500a(29) =0