a(n) = Sum_{k=0..n} 4^k * binomial(n/2+k-1,k) * binomial(n-1,n-k).
A378551
a(n) = Sum_{k=0..n} 4^k * binomial(n/2+k-1,k) * binomial(n-1,n-k).
Terms
- a(0) =1a(1) =2a(2) =20a(3) =206a(4) =2200a(5) =24062a(6) =267500a(7) =3009050a(8) =34150000a(9) =390265190a(10) =4484762500a(11) =51771831146a(12) =599921125000
External references
- oeis: A378551