Observations of the Cabibbo-Suppressed decays , and the Cabibbo-Favored decay *

Abstract Using electron-positron annihilation data samples corresponding to an integrated luminosity of 4.5 fb , collected by the BESIII detector in energy region between 4599.53\; \,{\rm{MeV}} and 4698.82\; we report first observations Cabibbo-suppressed decays \Lambda_c^+\to n\pi^+\pi^0 n\pi^+\pi^-\pi^+ Cabibbo-favored decay nK^-\pi^+\pi^+ with statistical significances 7.9\sigma 7.8\sigma >10\sigma respectively. The branching fractions these are measured be $\mathcal{B}(\Lambda_{c}^{+}\rightarrow n\pi^{+}\pi^{0})=(0.64\pm0.09\pm0.02)$?> %, n\pi^{+}\pi^{-}\pi^{+})=(0.45\pm 0.07\pm 0.03)$?> nK^{-}\pi^{+}\pi^{+})=(1.90\pm0.08\pm0.09)$?> where uncertainties second systematic. We find that fraction \Lambda_{c}^{+}\rightarrow n\pi^{+}\pi^{0} is about one order magnitude higher than n\pi^{+} .