a(n) = 2*((2*n-1)*a(n-1) - (n-2)!), with a(1) = 4, n > 1.

A302769

a(n) = 2*((2*n-1)*a(n-1) - (n-2)!), with a(1) = 4, n > 1.

Terms

    a(0) =4a(1) =22a(2) =218a(3) =3048a(4) =54852a(5) =1206696a(6) =31373856a(7) =941214240a(8) =32001274080

External references