Question: How to get the desire output for the codes

Help required to get the derire output  for the differential equation . I am attacing the codes and the sample output.

restart:
with(DETools):
a1:=m^2*((1-N)/(2-N))*(r/2)*Dp:
a2:=((1-N)*m^2/(2-N))*(((Nb-Nt)/64)*(r^5/6-h^2*r/2)-(B[r]/4)*(r^3/4-h^2*r/2)*(Nt/Nb)):
a3:=a1-a2:
a4:=r^2*a3:
DE1:=r^2*diff(v(r),r,r)+r*diff(v(r),r)-(m^2*r^2+1)*v(r)=a4:
b1:=dsolve(DE1,v(r)):

Please Wait...