#9 - Prime Sum Sudoku
Prime Sum Sudoku Standard Sudoku rules apply. Additionally, every diamond symbol between two cells means that the corresponding digits add up to a prime number (3, 5, 7, 11, 13 or 17). Conversely, the lack of a diamond symbol between two orthogonally adjacent cells means that the corresponding digits do not add up to a prime number. Penpa link: https://git.io/JDvcN