a(n) = Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} Sum_{l=1..n} (i+j+k+l)!/(4!*i!*j!*k!*l!).
A144662
a(n) = Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} Sum_{l=1..n} (i+j+k+l)!/(4!*i!*j!*k!*l!).
Terms
- a(0) =0a(1) =1a(2) =266a(3) =45296a(4) =7958726a(5) =1495388159a(6) =295887993624
External references
- oeis: A144662