Claude Opus 5's Disproof #6 targeted Conjecture 352, a total domination problem open since February 2009. The disproof found a unique minimum-order counterexample at exactly 18 vertices: all 81,134 trees with n at most 17 satisfy the conjecture, but exactly one of 123,867 trees at n=18 fails. An infinite family H(c) with n=8c+6 and deficit growing without bound was also constructed. This is the kind of precise mathematical result that makes for compelling investigative journalism.