1, 1, 2, 4, 10, 26, 73, 214, 651, 2040, 6549, 21453, 71485, 241702, 827603, 2865087, 10014927, 35307628, 125427569, 448616693, 1614432373, 5842129120, 21247505098, 77631329535, 284832049361, 1049092809734, 3877749157355, 14380314221305, 53490244751332