a(n) = 2^(n-1) * Sum_{k=0..n} ((n+k)!/(n-k)!)/k!.
A072331
a(n) = 2^(n-1) * Sum_{k=0..n} ((n+k)!/(n-k)!)/k!.
Terms
- a(0) =3a(1) =38a(2) =772a(3) =21768a(4) =786736a(5) =34703456a(6) =1807726656a(7) =108602413184
External references
- oeis: A072331
A072331
a(n) = 2^(n-1) * Sum_{k=0..n} ((n+k)!/(n-k)!)/k!.