Put the digits 0 to 6 – once each, into every row, column and box. To enable this, one cell in every row, column and box is a “Schrödinger cell” that contains two digits. This cell counts as the sum of its digits for the following rules. One cell in every row, column and box is a doubler. This cell counts as double its value for the following rules. Each of the digits 0 to 6 appears exactly once in a doubler cell. The sum of the cell values on a line within a 2x3 box must be the same for each box that line passes through. Eg the values of r4c2+r3c3 = the values of r2c4+r1c4+r2c5