I thank Richard Guy for his answer (negative) to the converse domino question I posed.

Can someone please tell me where to find the "Inquisiive Problem Solver" ?  I don't even know whether it's a magazine or website or what.

Somehow I don't think I associate Sol LeWitt's name with the problem I'm trying to recall.  It was posted by someone whose name I don't think I recognized then and don't recall now. (If you are that person, please forgive me.)

But it had to do with 4x4 arrangements of black & white squares such that each row and each column contains 2 W and 2 B squares.  The question was whether all such arrangements could be obtained in a certain way, which I don't remember, either.

--Dan