1, 1, 2, 4, 10, 23, 63, 155, 448, 1151, 3450, 9137, 28134, 76236, 239712, 661374, 2115046, 5921549, 19203568, 54422726, 178585838, 511343777, 1694965469, 4896195579, 16371992897, 47656781437, 160578870274, 470571482142, 1596323368095, 4705798878362, 16059653893209