Triangle read by rows: T(n, k) = (-1)^(k+1)*binomial(n,k)*binomial(n+k,k) (n >= k >= 0).

Terms

a(0) =-1a(1) =-1a(2) =2a(3) =-1a(4) =6a(5) =-6a(6) =-1a(7) =12a(8) =-30a(9) =20a(10) =-1a(11) =20a(12) =-90a(13) =140a(14) =-70a(15) =-1a(16) =30a(17) =-210a(18) =560a(19) =-630a(20) =252a(21) =-1a(22) =42a(23) =-420a(24) =1680a(25) =-3150a(26) =2772a(27) =-924a(28) =-1a(29) =56