a(n) = n*(n-1)*a(n-1)/2 + a(n-2), a(0) = 1, a(1) = 2.
A001052
a(n) = n*(n-1)*a(n-1)/2 + a(n-2), a(0) = 1, a(1) = 2.
Terms
- a(0) =1a(1) =2a(2) =3a(3) =11a(4) =69a(5) =701a(6) =10584a(7) =222965a(8) =6253604a(9) =225352709a(10) =10147125509a(11) =558317255704
External references
- oeis: A001052