a(n) = Sum_{0<=i<j<k<=n} (i+j+k)!/(i!*j!*k!).
A306432
a(n) = Sum_{0<=i<j<k<=n} (i+j+k)!/(i!*j!*k!).
Terms
- a(0) =0a(1) =0a(2) =3a(3) =77a(4) =1777a(5) =41088a(6) =964199a(7) =22962721a(8) =553886872a(9) =13504654074a(10) =332253097450
External references
- oeis: A306432