Vectorization for dependent loops

Hi i want vectorize this code :

    a(1)= 1 ;
    for g=1:len_1              % len_1 >> len_2
    for c=0:min(g-1,len_2)     % the use of min() is related to the positive sign of index g-c 
    a(g+1)=a(g+1)+k(c+1)*k(g-c)
    end
    end

in the same way as this situation:

k=zeros([1,10000]);
for i=1:10000;
k(i)=rand;
end

k=zeros([1,10000]);
a=1:10000;
k(a)=rand;

Any idea?