a(n) = (1/3)*A374654(n).A374655a(n) = (1/3)*A374654(n).Terms a(0) =1a(1) =2a(2) =8a(3) =40a(4) =320a(5) =3840a(6) =72960a(7) =2188800a(8) =105062400a(9) =8089804800External referencesoeis: A374655