Expansion of (1 - t)*(1 + t)^x.

Terms

a(0) =1a(1) =-1a(2) =1a(3) =0a(4) =-3a(5) =1a(6) =0a(7) =5a(8) =-6a(9) =1a(10) =0a(11) =-14a(12) =23a(13) =-10a(14) =1a(15) =0a(16) =54a(17) =-105a(18) =65a(19) =-15a(20) =1a(21) =0a(22) =-264a(23) =574a(24) =-435a(25) =145a(26) =-21a(27) =1a(28) =0a(29) =1560