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

A247249

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

Terms

    a(0) =1a(1) =1a(2) =4a(3) =22a(4) =166a(5) =1582a(6) =18232a(7) =246508a(8) =3825244a(9) =67001212a(10) =1307450224a(11) =28126466824a(12) =661290689416

External references