a(n) = Sum_{i=0..n} Sum_{j=0..n} Sum_{k=0..n} Sum_{l=0..n} (i+j+k+l)!/(i!*j!*k!*l!).
A144661
a(n) = Sum_{i=0..n} Sum_{j=0..n} Sum_{k=0..n} Sum_{l=0..n} (i+j+k+l)!/(i!*j!*k!*l!).
Terms
- a(0) =1a(1) =65a(2) =7365a(3) =1107697a(4) =191448941a(5) =35899051101
External references
- oeis: A144661