This has fundamental solutions , (9, 3), and (19, 17), giving the family of solutions
(5, 1), (9, 3), (19, 17), (61, 23), (135, 51), (509, 193), .... These give solutions
which are integers in and of , (10, 13), (39025, 51625), ... (OEIS A048916
and A048917), giving the nonagonal hexagonal
numbers 1, 325, 5330229625, 1353857339341, 22184715227362706161, ... (OEIS A048918).