3-j symbols and Clebsch–Gordan coefficients address the same physical problem of adding angular momenta, but 3-j symbols do so with more symmetry.
Notes on verification
Directly corroborated by Wikipedia and multiple independent physics sources, with consistent agreement and no contradictions. This is a well-established mathematical physics fact within the quantum mechanics/angular momentum coupling literature.
Sources
- 3-j symbol (en.wikipedia.org)
- https://www.theochem.ru.nl/~pwormer/Knowino/knowino.org/wiki/3j-symbol.html (theochem.ru.nl)
- https://arxiv.org/pdf/1303.3246 (arxiv.org)
- https://arxiv.org/pdf/1402.7051 (arxiv.org)
- https://www.sciencedirect.com/topics/physics-and-astronomy/clebsch-gordan-coefficient (sciencedirect.com)