a(n) = Sum_{k=0..n} (3*n-2*k)!/((n-k)!^3*k!)*(-3)^k, n >= 0.
A318108
a(n) = Sum_{k=0..n} (3*n-2*k)!/((n-k)!^3*k!)*(-3)^k, n >= 0.
Terms
- a(0) =1a(1) =3a(2) =27a(3) =303a(4) =3771a(5) =49653a(6) =677979a(7) =9496791a(8) =135572859a(9) =1963940073a(10) =28783474677a(11) =425872190241
External references
- oeis: A318108