Triangle read by rows: T(n,k)=(-1)^k*(2n/(2n-k))5^(n-k)*binomial(2n-k,k) (0<=k<=n, n>=1).

Terms

a(0) =5a(1) =-2a(2) =25a(3) =-20a(4) =2a(5) =125a(6) =-150a(7) =45a(8) =-2a(9) =625a(10) =-1000a(11) =500a(12) =-80a(13) =2a(14) =3125a(15) =-6250a(16) =4375a(17) =-1250a(18) =125a(19) =-2a(20) =15625a(21) =-37500a(22) =33750a(23) =-14000a(24) =2625a(25) =-180a(26) =2a(27) =78125a(28) =-218750a(29) =240625