a(n) = (n-3)*a(n-1) + a(n-4), with a(1)=0, a(2)=1, a(3)=2, a(4)=3.

A121959

a(n) = (n-3)*a(n-1) + a(n-4), with a(1)=0, a(2)=1, a(3)=2, a(4)=3.

Terms

    a(0) =0a(1) =1a(2) =2a(3) =3a(4) =6a(5) =19a(6) =78a(7) =393a(8) =2364a(9) =16567a(10) =132614a(11) =1193919a(12) =11941554a(13) =131373661a(14) =1576616546a(15) =20497209017a(16) =286972867792

External references