A Seidel matrix A(n,k) read by antidiagonals upwards.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =0a(5) =-1a(6) =-2a(7) =-3a(8) =-3a(9) =-2a(10) =-5a(11) =-3a(12) =0a(13) =3a(14) =5a(15) =16a(16) =21a(17) =24a(18) =24a(19) =21a(20) =16a(21) =61a(22) =45a(23) =24a(24) =0a(25) =-24a(26) =-45a(27) =-61a(28) =-272a(29) =-333