Date: 201809
Local time of day: 0601-1200
Location: BNA.Airport, TN
Aircraft: EMB ERJ 170/175 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower BNA
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Not Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Communication Breakdown; Distraction; Human-Machine Interface
Second reporter function: First Officer; Pilot Flying
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Taxi
Result: Flight Crew Rejected Takeoff
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: Leaving the gate at BNA we were expecting Runway 20R for departure. Once we got to Spot 4 we were assigned a quick release time and to expect Runway 20C; a shorter taxi. There were about 4-5 aircraft that had pushed or were in the process of pushing; all departing Runway 20C. We taxied via T4; crossing 31; and held short of S7 for a passing aircraft. The First Officer had started entering in the new runway and sent for new takeoff data. I requested for him to start engine number 2; but seeing that he was busy entering in the new data; I told him I would get the engine started. Ground Control inquired if we would be ready to go in sequence (number 3 or 4 for departure) and I told the First Officer to let them know that we would. While starting the engine we began to get a printout to add an alternate since the weather in ZZZ now required it. Admittedly; I turned my attention to the printout to see what it was and once I looked back to the gauges I noticed the number 2 was not starting. I attempted to start the engine again. Once again; with the distraction of the runway change; new alternate; short release time; and multiple aircraft waiting to depart; the number 2 failed to start and I had failed to notice. Once holding short of 20C we ran the taxi checklist at which time the First Officer pressed the T/O CONFIG button and we were given the okay. However; neither of us had verified the number 2 engine had started and as we rolled onto the runway I was checking that we had speeds set; ROLL/TO displayed; etc.; but never turned my attention to the engine gauges. It was the First Officer's leg; and once cleared for takeoff he pushed the throttles forward. It was then that we both noticed that the second engine was not started. We aborted the takeoff roll and taxied off. Once on taxiway we started the second engine; got back in sequence; and departed with no issues.This was clearly a mistake on my part to not get a new departure time and slow down to make sure we were not task saturated. Better situational awareness to slow down and not let the situation dictate my readiness. Also; a better cross scan of all gauges and parameters. For what it's worth; a takeoff configuration button that doesn't recognize an inoperative engine and gives the okay regardless; seems odd. I understand this doesn't relieve the crew of all responsibility; but it does provide a false sense of security and readiness.


Second narrative: [Report narrative contained no additional information.]


Synopsis: EMB-175 flight crew reported becoming task saturated on taxi and forgot to start second engine when cleared for takeoff.