def cs_gn(A):
	"""Cross section for A(g,n)X averaged over E[.3, 1.] GeV
	
	Returns cross section of photoneutron production averaged
	over the energy range [.3, 1.] GeV, in milibarn units.
	
	Arguments:
		A {int} -- Nucleon number of the target nucleus
	"""

	return 0.104 * A**0.81