A027160 a(n) = T(2n,n-2), T given by A027157.
5, 21, 176, 680, 5808, 21840, 190976, 708480, 6310400, 23220736, 209756160, 767676416, 7010676736, 25558732800, 235443322880, 855858053120, 7939647995904, 28796047982592, 268690773770240, 972740537352192, 9120760620646400
Offset: 2