From eqtraders.com, dated 2003-05-20:
http://www.eqtraders.com/articles/ar...r=040095000000
Per spell rank trivials, but for wizard research:
Trivials for Wizard Research spells:
Level 16 Spells - Trivial at 26.
Level 20 Spells - Trivial at 46.
Level 24 Spells - Trivial at 71.
Level 29 Spells - Trivial at 96.
Level 34 Spells - Trivial at 120.
Level 39 Spells - Trivial at 140.
Level 44 Spells - Trivial at 166.
Level 49 Spells - Trivial at 184.
Admittedly not for magicians, but quite close to known mage research trivials from here:
http://www.magecompendium.com/research-library.html