Studied with the Saturn A-1 in 1959, the Saturn A-2 was deemed more powerful than the Saturn I rocket. It was proposed as a launcher for Project Horizon, a scientific / military base on the Moon project, at a time when the U.S. Department of the Army, Department of the Navy, and Department of the Air Force had total responsibility for U.S. space program plans.
The rocket consisting of a S-IB first stage with eight H-1 engines (which actually flew on the Saturn IB), a Jupiter Cluster second stage equipped which four LR79 engines (used on the Jupiter IRBM) and a Centaur C high-energy liquid-fueled third stage with a double RL10A-1 engine.
See also
S-I Saturn I Juno V Titan I Centaur Project Horizon
References
Koelle, Heinz Hermann, Handbook of Astronautical Engineering, McGraw-Hill, New York, 1961. Bilstein, Roger E, Stages to Saturn, US Government Printing Office, 1980. .