how to sum of double Product of Series

Hallo Everyone

I am trying to solve this Equation in Matlab but it gives always error for me

the Equation as follow

the answwer of this should be as follow

for

I have tried with for loop as follows but not working

D_sum_Dy = 0;
n_cyc_t = [1,31,32,1];

for g=1:length(n_cyc_t)
   if g > 1
   for j=1:(g-1)
     
       for k=1:j

           syms N n g k j
           g_1 = symprod(N(j)/N(j+1),j,1,(g-1))^(symprod(exp(-n(k)/N(k))-exp(-1)/(1-exp(-1)),k,1,j)-1);
           D_sum_Dy = D_sum_Dy+(n/N)*g_1;
           
       end
       
   end
   
end

Thank you for any help Or if there is easier way to solve it