a(n) = Sum_{k=0..n} (-4)^k*binomial(n,k)^2*binomial(n-k,k)^2.

A179524

a(n) = Sum_{k=0..n} (-4)^k*binomial(n,k)^2*binomial(n-k,k)^2.

Terms

    a(0) =1a(1) =1a(2) =-15a(3) =-143a(4) =1a(5) =12801a(6) =100401a(7) =-555855a(8) =-16006143a(9) =-69903359a(10) =1371541105a(11) =20881151985a(12) =5878439425

External references