Triangle: signed version of A055134.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =-2a(5) =1a(6) =-8a(7) =12a(8) =-6a(9) =1a(10) =81a(11) =-108a(12) =54a(13) =-12a(14) =1a(15) =-1024a(16) =1280a(17) =-640a(18) =160a(19) =-20a(20) =1a(21) =15625a(22) =-18750a(23) =9375a(24) =-2500a(25) =375a(26) =-30a(27) =1a(28) =-279936a(29) =326592