a(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(4*n-2*k-2,n-2*k).
A390685
a(n) = Sum_{k=0..floor(n/2)} (-1)^k * binomial(4*n-2*k-2,n-2*k).
Terms
- a(0) =1a(1) =2a(2) =14a(3) =112a(4) =936a(5) =8022a(6) =69920a(7) =616816a(8) =5490860a(9) =49224656a(10) =443782794a(11) =4019371712a(12) =36543625868a(13) =333329554820
External references
- oeis: A390685