DC-6/7 types were normally started 3-4-2-1.
Hydraulic pumps on two and three.
In addition, and this could be quite important...in the event of a fire whilst starting, starting the inboard engine first on four engine types provided better access for the fire guard.
And...to anticipate the next question, if hydraulic pumps were on engines two and three, what accessory was driven by numbers one and four?
Among others...cabin superchargers (roots blowers).
And yes, I flew both types mentioned.