how to make a Series?

Hello, I am trying to create a series like this:

X(n)=-(sqrt(n)-Sqrt(n-1))x(1)-(sqrt(n-1)-sqrt(n-2))x(2)-(sqrt(n-2)-sqrt(n-3))x(3)+......+1/(1+exp(-an))

So, if n=1:

x(1)=1/(1+exp(-a))

if n=2:

x(2)=-(sqrt(2)-1)x(1)+1/(1+exp(-2a))

and so on. I have never worked with series at MATLAB. I can find any way to create the series, however, i am wondering if there are some specific rule.

Thanks a lot.

Answer 1

[Roger Stafford]

   x = zeros(N,1);
   for n = 1:N
     x(n) = sum(-(sqrt(n:-1:2)-sqrt(n-1:-1:1)).*x(1:n-1))+1/(+exp(-a*n));
   end

[Roger Stafford]

It would save excessive square roots to write

   x = zeros(N,1);
   s = sqrt(1:N);
   for n = 1:N
     x(n) = sum((s(n-1:-1:1)-s(n:-1:2)).*x(1:n-1))+1/(+exp(-a*n));
   end

[sama]

Thanks a lot.