Whichmxnrectangles can be tiled with copies of an L-shaped union of three unit squares?

Source:Problem 10641 in the current issue (Feb 1998) of the Amer. Math. Monthly. This problem is "live" and if you solve it you can submit your solution to the AMM. Thus I willnotpost a solution, give hints, or comment on submissions (and request the same for any of you who solve it). The proposer is Jerrold Griggs from the University of South Carolina. (My thanks to Macalester student Vahe Poladian for working out the solution.)© Copyright 1998 Stan Wagon. Reproduced with permission.

2 October 1998