A067722 Least number k such that n (n + k) is a perfect square.

1, 3, 6, 9, 5, 15, 18, 21, 10, 7, 30, 33, 15, 39, 42, 45, 9, 51, 14, 57, 25, 63, 66, 69, 30, 11, 78, 21, 35, 87, 90, 93, 18, 99, 102, 105, 13, 111, 114, 117, 50, 123, 126, 129, 55, 35, 138, 141, 27, 15, 22, 153, 65, 159, 42, 165, 70, 171, 174, 177, 75, 183, 186, 49, 17