BeginPackage["cefactor`","nuclcoor`"]
cefactor::usage:=
"The cefactor[a,z] evaluates the Coulomb energy factor, which is
defined as 1 for two adjacent protons. To evaluate the factor type
in as the first argument a - the mass number, and as the second
argument z - the atomic number.\nCurrently, the data comprise the
following nuclei: He-4, O-16, Ne-20, Ar-40, Ca-40, Fe-56, Se-80,
Sn-120, Ce-140, Pb-208, U-238 and Uk-332, an unknown the most stable
superheavy nucleus with the atomic number 122."
Begin["`private`"]
cefactor/: cefactor[a_,z_]:=(p=pc[a,z];
If[Length[p]!=z,Return[Message[cefactor::usage]],cef[z]=f[z]])
f/: f[1]=0
f/: f[k_]:=
N[f[k-1]+Sqrt[8]*Sum[1/Sqrt[(p[[i]]-p[[k]]).(p[[i]]-p[[k]])],{i,k-1}]]
End[]
EndPackage[]