"One" is a song by American singer-songwriter #HarryNilsson from his 1968 album #AerialBallet. It is known for its #openingLine "One is the loneliest number that you'll ever do". Nilsson wrote the song after calling someone and getting a #busySignal. He stayed on the line listening to the "beep, beep, beep, beep..." tone, writing the song. The busy signal became the opening notes. A better-known #coverVersion, recorded by #ThreeDogNight.
https://www.youtube.com/watch?v=l5261s3Z3RU