a(n) = Sum_{k=0..n} (3*n)!/(k! * (n-k)!)^3.
A306642
a(n) = Sum_{k=0..n} (3*n)!/(k! * (n-k)!)^3.
Terms
- a(0) =1a(1) =12a(2) =900a(3) =94080a(4) =11988900a(5) =1704214512a(6) =260453217024
External references
- oeis: A306642
A306642
a(n) = Sum_{k=0..n} (3*n)!/(k! * (n-k)!)^3.