@AmusingYeti The development of probability theory resulted from the earnest contemplation of problems faced by gamblers. In the 20th century, much progress in computer science resulted from trying to program a machine to play chess.
Recreational math may seem like an oxymoron to some. The term broadly includes puzzles such as Sudoku where no advanced knowledge of mathematics is required yet still involves the same logic and deductive skills used in mathematics.
Martin Gardner's Mathematical games in the back of Scientific American I think would be a great example of recreational math.
Majorie rice in 1975, with no math beyond high school discovered four new tessellations, as a result of in my opinion "recreational math".
So by no means should we not consider recreation and math in the same sentence. Math and Recreational math are both serious business.