| Date | Subject |
|---|---|
| January 26, 1996 | PALINDROMES |
| October 18, 2001 | The man in the park |
| September 10, 2009 | Two numbers |
| December 15, 2009 | Integer right triangles |
| March 18, 2011 | Yet another sequence |
| August 9, 2011 | Cotpi 16 - Chessboard of averages |
| August 19, 2011 | Enigma 1654 - Tricky cards |