a(n) = n*a(n-1) + (n-3)*a(n-2), with a(1) = 0, a(2) = 1.
A000261
a(n) = n*a(n-1) + (n-3)*a(n-2), with a(1) = 0, a(2) = 1.
Terms
- a(0) =0a(1) =1a(2) =3a(3) =13a(4) =71a(5) =465a(6) =3539a(7) =30637a(8) =296967a(9) =3184129a(10) =37401155a(11) =477471021a(12) =6581134823a(13) =97388068753
External references
- oeis: A000261