a(0) = 1; a(1) = 1; a(2) = 1; a(n) = (n-1)*a(n-1) + (n-2)*a(n-2) + (n-3)*a(n-3) for n >= 3.
A122752
a(0) = 1; a(1) = 1; a(2) = 1; a(n) = (n-1)*a(n-1) + (n-2)*a(n-2) + (n-3)*a(n-3) for n >= 3.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =3a(4) =12a(5) =59a(6) =352a(7) =2455a(8) =19592a(9) =176033a(10) =1758218a(11) =19323213a(12) =231721820a(13) =3010799363a(14) =42133608902a(15) =631791578187
External references
- oeis: A122752