Logic Masters Deutschland e.V.

Normal Sudoku rules apply.

Multiplying by 2 then adding 1 to the digit in an arrow circle gives you the sum of the attached digits along that arrow.
For example, if an arrow circle contains a 7, the digits along that arrow's path need to sum up to 7*2+1 = 15.
Digits may repeat along an arrow if allowed by other rules.

Cells that are a knight's move (in chess) away from each other cannot contain the same digit.

F-puzzles link