a(n) = n! * (n+1)! * (n+2)! * Sum_{k=0..n} 1/(6^(n-k) * k! * (k+1)! * (k+2)!).
A368840
a(n) = n! * (n+1)! * (n+2)! * Sum_{k=0..n} 1/(6^(n-k) * k! * (k+1)! * (k+2)!).
Terms
- a(0) =1a(1) =2a(2) =9a(3) =91a(4) =1821a(5) =63736a(6) =3569217a(7) =299814229a(8) =35977707481
External references
- oeis: A368840