a(n) = (n-1)!*Sum_{i=1..n-1} (-1)^(i+1)*A027907(n-i+2,i+1)*a(n-i)/(n-i)! for n>0 with a(0)=1, where A027907 is the triangle of trinomial coefficients.
A136168
a(n) = (n-1)!*Sum_{i=1..n-1} (-1)^(i+1)*A027907(n-i+2,i+1)*a(n-i)/(n-i)! for n>0 with a(0)=1, where A027907 is the triangle of trinomial coefficients.
Terms
- a(0) =1a(1) =3a(2) =16a(3) =120a(4) =1140a(5) =12972a(6) =171216a(7) =2571912a(8) =43429680a(9) =816108048a(10) =16894168704a(11) =381536713152
External references
- oeis: A136168