a(n) = Sum_{i+j+k=n, 0<=i<=j<=k<=n} (n+2*i)!/((2*i)! * j! * k!).
A092470
a(n) = Sum_{i+j+k=n, 0<=i<=j<=k<=n} (n+2*i)!/((2*i)! * j! * k!).
Terms
- a(0) =1a(1) =3a(2) =42a(3) =774a(4) =19440a(5) =605520a(6) =22856400a(7) =1012258800a(8) =51590125440
External references
- oeis: A092470