One reasonable and memorable approximation excluding any fine structure is:
see for example example: hydrogen 1-2 spectral line.
Equation 24. Hydrogen spectral series mnemonic
- Hydrogen emission spectrum | 0, 117, 2
- Spectral line | 165, 1k, 11
- Emission spectrum | 0, 1k, 12
- Quantum mechanics experiment | 66, 2k, 22
- Quantum mechanics | 169, 20k, 270
- Particle physics | 137, 32k, 512
- Physics | 276, 46k, 825
- Natural science | 0, 61k, 2k
- Science | 0, 66k, 2k
- Ciro Santilli's Homepage | 262, 218k, 4k