Don't need the online integrator any more when I can do this:   #maths #computing #python 
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<br />from sympy import *
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<br />b,C,D = symbols('b C D')
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<br />print(integrate(C/(1+(b*D)**2)*2*pi*b, b))
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<br />Output:   pi*C*log(D**2*b**2 + 1)/D**2