Balmer noticed that a single number had a relation to every line in the hydrogen spectrum that was in the visible light region. That number was 364.50682 nm. When any integer higher than 2 was squared and then divided by itself squared minus 4, then that number multiplied by 364.50682 gave a wavelength of another line in the hydrogen spectrum.
The Balmer equation can be used to find the wavelength of the absorption/emission lines.
|λ||Wavelength of the absorption/emission (nm)|
|n||Integer such that n > 2 (dimensionless)|