A031968 n-th number in which the number of distinct base 9 digits is 4.

750, 751, 752, 753, 754, 755, 758, 760, 761, 762, 763, 764, 767, 768, 770, 771, 772, 773, 776, 777, 778, 780, 781, 782, 785, 786, 787, 788, 790, 791, 794, 795, 796, 797, 798, 800, 803, 804, 805, 806, 807, 808, 894, 895, 896