Constant X=[253,258,263,268,273,278,288,298,308,318,328,333,338,343,348],
Y=[44.146,33.34,25.1569,19.23205,14.85534,11.54506,7.15712,4.56783,2.95356,2.01334,1.41186,1.210149,1.006474,0.912868,0.78728];
Function Sum(i=1:15,X,Y)(ln(a)-b*((1/X-1/298)-c*(1/X-1/298)^2)-Y)^2;