a(n) = Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} (i+j+k)!/(i!*j!*k!).
A144658
a(n) = Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} (i+j+k)!/(i!*j!*k!).
Terms
- a(0) =0a(1) =6a(2) =222a(3) =5052a(4) =109512a(5) =2432448a(6) =55611294a(7) =1301187912a(8) =30992726652a(9) =748573575780
External references
- oeis: A144658