It's a Boeing-built B-17F-115-BO, from production block 42-30617 to 42-30731.
The large numerals of the 'last three' of the serial number, in white, below the yellow numerals of the serial itself, and the relatively new look of the leather flying clothing, suggest the photo was taken 'Stateside' at a training establishment, or perhaps just prior to departure for the ETO, as these would not be present in a combat unit, and would be replaced by the unit identifier (for example 'Triangle A' of the 1st BD), and the individual aircraft code letter of that unit.
I've checked the serial against aircraft serving with the 1st Bombardment Division, 8th USAAF, and although other aircraft from this serial block were assigned to that division, this aircraft was not one of them.
It's possible that the aircraft was assigned to another combat unit, or it may have remained in the USA with a training unit.