a(n) = Sum_{i=0..n} Sum_{j=0..n} Sum_{k=0..n} (i+j+k)!/(i!*j!*k!).

A144660

a(n) = Sum_{i=0..n} Sum_{j=0..n} Sum_{k=0..n} (i+j+k)!/(i!*j!*k!).

Terms

    a(0) =1a(1) =16a(2) =271a(3) =5248a(4) =110251a(5) =2435200a(6) =55621567a(7) =1301226496a(8) =30992872483a(9) =748574130016

External references