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%%  Ein Beispiel der DANTE-Edition
%%  Mathematiksatz mit LaTeX
%%  3. Auflage
%%  Beispiel 04-05-14 auf Seite 45.
%%  Copyright (C) 2018 Herbert Voss
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\begin{document}
\begin{eqnarray}
  B(r,\phi,\lambda) & = & \,\frac{\mu}{r}
    \Bigg[\sum_{n=2}^{\infty}\Bigg(\left(\frac{R_e}{r}\right)^n J_nP_n(s\phi)\nonumber\\
  & & {}+\sum_{m=1}^n \left( \frac{R_e}{r} \right) ^n
   (C_{nm}\cos m\lambda+S_{nm}\sin m\lambda)P_{nm}(s\phi) \Bigg)\Bigg]
\end{eqnarray}
\end{document}