From Sudoku 17:
Free / Gratis SuDoKu17
Why SuDoKu17, this is the minimum amount of starting numbers that you can find a single solution from. Any less than this will produce multiple solutions failing to qualify as a true Sudoku puzzle.
Try our totally free / gratis SuDoKu17.exe or SuDoKu17.rar, with 293,024 puzzles.
Designed for Windows XP. Works on VISTA, Windows 7 & 8.
Originally sold from OneDollarSuDoKu.com back in 2006. Executable size (3,265,916 bytes) no install. One file. This application can also provide proof that the current puzzle is correct having only one solution. You can pick from any of the built in puzzles or add your own, with a minimum of 17 starting numbers. Clues can be turned on and off at any stage, good for learning.
Over the weekend 22nd/23rd June 2013 i discovered over 250,000 new valid starts. The new version of SuDoKu17 has 293,024 valid 17 clue puzzles. Latest build 30th June 2013. Results of Virus scan on SuDoKu17.exe can be found here www.virustotal.com