It's Odd Outside
The brief
- Normal sudoku rules apply, i.e. each row, column, and 3x3 box has to contain the digits from 1 to 9 once each.
- Up to N-sums: A clue outside the Row or Column N indicates the sum of all digits up to the cell that contains the digit N. (The digit N itself is not included in the sum.) For example, if Row 1 reads 234156789, it would have an Up to N-sum clue of 2+3+4=9 because 2, 3 and 4 are the digits appearing before the row number N=1.