Normal sudoku rules apply. Nine cells (one in each row, column and 3x3 box) are “doublers”, and have a value equal to double their digit. Each digit appears in exactly one doubler. The values of cells in a cage sum to the small clue in the top left corner of the cage. Digits may not repeat in a cage (though values may repeat). In row N (for all N from 1 to 9), the values of cells in the pill (read from left to right) give the row and column number of the doubler with the digit N.