Ancient Web: Erich Friedman Posted a Math Puzzle Every Month for Twenty Years

Part of the Ancient Web Collection.

A mathematician posts a hard puzzle. Readers send solutions. The next month, he posts another. Repeat for more than twenty years, and the result is something larger than a hobby.

Explore Erich Friedman's Math Magic Archive.

Friedman's main homepage has several mathematical and personal sections, but the most revealing is this record of monthly recreational problems. The archive opens with Divisor Chains in November 1998 and Integer Square Tilings in December. It then runs through 2020, with links both by calendar year and by problem family.

Problems do not necessarily end when the month does

Each index entry carries its original month and often a much later update date. An early problem about Convex Spectra, for instance, lists an update in 2021. Others from 1999 were revised in 2002, 2007, or 2017. The collection shows mathematical puzzles as ongoing conversations: a solution can be improved, an unresolved case can be settled, and someone can send a new observation long after the original question has left the homepage.

The categories reveal the range of interests: tilings, polyominoes, square and circle packing, graphs, matrices, chess, number games, and digit tricks. Among the 2000 entries are Longest Sokoban Games, Counting Domino Tilings, and Friedman Numbers. The archive makes it possible to follow an entire strand of curiosity rather than only look at the month's answer.

The surrounding homepage adds a Packing Center, Puzzle Palace, ambigrams, a mathematical genealogy section, and a periodic table of mathematicians. This is an individual choosing how to arrange a personal research playground—not an algorithm grouping posts by engagement.

The index states that Friedman posed unsolved recreational problems and posted solutions he received. That is the site's own description of its process; the visible sequence and dated revisions demonstrate the continuing work without needing claims about its number of readers.

An old website is sometimes historically important because a particular page became famous. Here the importance lies in repeated maintenance. A simple HTML archive quietly records the intellectual generosity required to keep a conversation open from the dial-up era into the smartphone era.

Browse the problems by year or category.

Part of the Ancient Web Collection.