Sometimes when you copy and paste there might be hidden characters or other weirdness.
Try erasing and then typing out k={6*($>+1)} . Also, erase the and retype the spaces on either side.
Sometimes when you copy and paste there might be hidden characters or other weirdness.
Try erasing and then typing out k={6*($>+1)} . Also, erase the and retype the spaces on either side.