a(n) = (n-1)*a(n-1) - a(n-2) + (n-2)*a(n-3) with a(0)=a(1)=1, a(2)=0.
A269509
a(n) = (n-1)*a(n-1) - a(n-2) + (n-2)*a(n-3) with a(0)=a(1)=1, a(2)=0.
Terms
- a(0) =1a(1) =1a(2) =0a(3) =0a(4) =2a(5) =8a(6) =38a(7) =230a(8) =1620a(9) =12996a(10) =117184a(11) =1173424a(12) =12920440a(13) =155160880a(14) =2018252088a(15) =28268334072a(16) =424179011312
External references
- oeis: A269509