We evaluate the connection between the bound-state energy spectrum for 
two nucleons in a harmonic-oscillator (HO) trap and their scattering 
phase shift in the continuum with the interaction being the 
one-pion-exchange-potential (OPEP). In this work, the 1S0 and 3S1-3D1 
channels are considered. We show that a direct implementation of the 
Busch's formula converts the bound-state energy in the HO trap to the 
scattering phase shift in the continuum in the 1S0 channel. For the 
3S1-3D1 channel, we derive a generalization of the Busch's formula to 
connect the bound-state energy to the scattering phase shifts and 
evaluate its error. Our results could enable the study of an effective 
field theory approach to the no-core shell model (NCSM) in a higher 
energy region.