a(n) = Sum_{k = 0..n} (-4)^(n-k)*binomial(n,k)*binomial(3*n+k,k)*binomial(2*k,k).
A363987
a(n) = Sum_{k = 0..n} (-4)^(n-k)*binomial(n,k)*binomial(3*n+k,k)*binomial(2*k,k).
Terms
- a(0) =1a(1) =4a(2) =72a(3) =1336a(4) =27816a(5) =609504a(6) =13849776a(7) =322761632a(8) =7665078696a(9) =184706717728
External references
- oeis: A363987