a(n) = v(n+1)/v(n), where v=A203518.A203519a(n) = v(n+1)/v(n), where v=A203518.Terms a(0) =3a(1) =20a(2) =336a(3) =12870a(4) =1270080a(5) =311323584a(6) =197399802600External referencesoeis: A203519