a(n) = 1/exp(1) * Sum_{k>=0} (k+n)!^2 / k!^3.
A069948
a(n) = 1/exp(1) * Sum_{k>=0} (k+n)!^2 / k!^3.
Terms
- a(0) =1a(1) =5a(2) =87a(3) =2971a(4) =163121a(5) =12962661a(6) =1395857215a(7) =194634226067
External references
- oeis: A069948
A069948
a(n) = 1/exp(1) * Sum_{k>=0} (k+n)!^2 / k!^3.