Signed double Pochhammer triangle: expansion of x(x-2)(x-4)..(x-2n+2).

Terms

a(0) =1a(1) =-2a(2) =1a(3) =8a(4) =-6a(5) =1a(6) =-48a(7) =44a(8) =-12a(9) =1a(10) =384a(11) =-400a(12) =140a(13) =-20a(14) =1a(15) =-3840a(16) =4384a(17) =-1800a(18) =340a(19) =-30a(20) =1a(21) =46080a(22) =-56448a(23) =25984a(24) =-5880a(25) =700a(26) =-42a(27) =1a(28) =-645120a(29) =836352