Number triangle T(n,k)=sum{i=0..n, (-1)^(n-i)*C(n,i)*sum{j=0..i-k, C(k,2j)*C(i-k,2j)}}.

Terms

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