Skyscrapers. Put a number between 1 and the length of a side of the grid such that each number appears exactly once in each row and column. If the numbers represent heights of buildings, the numbers outside the grid tell the number of visible buildings from that point looking into the grid, with higher buildings block lower ones in visibility. This one is somewhat easy.
Easy enough isn’t it? Puzzle 20, the 17×17 puzzle, will be a Fillomino and will be posted in 12 hours from this post.