A025270 a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ...+ a(n-1)*a(1) for n >= 5.

1, 2, 1, 1, 6, 17, 60, 201, 688, 2370, 8218, 28703, 100846, 356370, 1265918, 4518571, 16200070, 58317298, 210718174, 764015412, 2778955460, 10137598506, 37082361204, 135985402371, 499840932062, 1841260760276, 6796395432602, 25134116857096