where , and
Richtmyer and Greenspan obtained the 512 initial terms of that expansion, but here I present only several of them:
Not all terms are independent, due to Jacobi identities.
- T1267: R.D. Richtmyer and S. Greenspan: “Expansion of the Campbell-Baker-Hausdorff formula by Computer”; Communications on Pure and Applied Mathematics, Vol XVIII 107-108 (1965).