a(n) = (n+1)*a(n-1) + (n+2)*a(n-2) + a(n-3); a(1)=0, a(2)=3, a(3)=13.
A000904
a(n) = (n+1)*a(n-1) + (n+2)*a(n-2) + a(n-3); a(1)=0, a(2)=3, a(3)=13.
Terms
- a(0) =0a(1) =3a(2) =13a(3) =83a(4) =592a(5) =4821a(6) =43979a(7) =444613a(8) =4934720a(9) =59661255a(10) =780531033a(11) =10987095719a(12) =165586966816
External references
- oeis: A000904