There are only twelve 4x4 sudokus - and a cool trick for finding minimal subsets
Summary
This article analyzes how many 4x4 Sudoku solutions exist and how many are structurally distinct under digit permutations. It uses brute-force Python code to enumerate total and distinct solutions, discusses a trick to count distinct structures by fixing the first row, and presents the resulting counts (288 total solutions, 12 distinct structures, and 85632 puzzles).