a(n) = w(n+1)/(4*w(n)), where w = A203426.

A203427

a(n) = w(n+1)/(4*w(n)), where w = A203426.

Terms

    a(0) =-3a(1) =48a(2) =-1000a(3) =25920a(4) =-806736a(5) =29360128a(6) =-1224440064a(7) =57600000000

External references