Hell no. If they batteries had an Output of 2600mA and I wanted to get 7.2V, 2600mA, I would need that many batteries.
But I'm not talking about Amperage, I'm talking about Charge (which is what they store, not what they put out).
So I would always get 15600mAh while it's irrelevant how I wire them.
Okay. Honestly. When you wire batteries in series, it works just like wiring anything else in series, you increase the voltage (not current). When you wire batteries in parallel, it works just like wiring anything else in parallel, you increase the current (not voltage).http://batteryuniversity.com/index.php/learn/article/serial_and_parallel_battery_configurations
If you don't believe us, hook up your batteries in series, then hook up your portable to it. Measure the current draw with a multimeter (or use the approximations from us), use a stopwatch to record the runtime, and you can figure out the mAH pretty easily. Current draw will be something around 2.5-3 amps, and it will run for about an hour, which puts it pretty close to 2600mAH.