How long would these batteries run for? Does voltage change runtimes

So let's say I have FOUR 3.7v Lithium batteries. Each battery has 4000 mAh.

CONFIGURATION 1: Batteries in Parallel.= 3.7v @ 16000mAh
CONFIGURATION 2: Batteries in Series = 14.8v @ 4000mAh

So let's say I can regulate the output of either configuration to 3.7volts.

If I connected a 3.7v load (say a light bulb or something) that draws 1A of power, which configuration would run the longest? What would be the run-times?

Thanks

The parallel connection. in that case, you