Triangle read by rows, T(n, k) = [x^k] -hypergeom([-1/2, -n, -n], [1, 1], 4*x).

Terms

a(0) =-1a(1) =-1a(2) =2a(3) =-1a(4) =8a(5) =2a(6) =-1a(7) =18a(8) =18a(9) =4a(10) =-1a(11) =32a(12) =72a(13) =64a(14) =10a(15) =-1a(16) =50a(17) =200a(18) =400a(19) =250a(20) =28a(21) =-1a(22) =72a(23) =450a(24) =1600a(25) =2250a(26) =1008a(27) =84a(28) =-1a(29) =98