y= 200 + 66.87*(exp( -0.0146*a0*x) +0.25*exp( -0.25*0.0146*a0*x) +1/9*exp(-1/9*0.0146*a0*x) +1/16*exp(-1/16*0.0146*a0*x) +1/25*exp(-1/25*0.0146*a0*x) +1/36*exp(-1/36*0.0146*a0*x)  +1/49*exp(-1/49*0.0146*a0*x)  +1/64*exp(-1/64*0.0146*a0*x) +1/81*exp(-1/81*0.0146*a0*x) +1/100*exp(-1/100*0.0146*a0*x) )