a(n) = (2*n+1)*a(n-1) - a(n-2) starting a(0)=0, a(1)=1.

A121323

a(n) = (2*n+1)*a(n-1) - a(n-2) starting a(0)=0, a(1)=1.

Terms

    a(0) =0a(1) =1a(2) =5a(3) =34a(4) =301a(5) =3277a(6) =42300a(7) =631223a(8) =10688491a(9) =202450106a(10) =4240763735a(11) =97335115799

External references