I was looking at this picture of an Ilyushin IL-18 turboprop aircraft
Image hosted at https://i2.cdn.turner.com/cnnnext/dam/assets/160630220221-north-korea-air-koryo-il-18-nose-super-169.jpg
and noticed that the outboard engines look significantly smaller than the inboard engines. Wikipedia lists specifications for four identical engines but the outboard cowlings don't seem to have air intakes.
Can anyone explain why?