Certainly, here's the Octave code for Newton's divided difference interpolation for your specific data points:

```octave
x = [15, 20];
y = [362.78, 517.35];
t = 16;

n = length(x);
result = y(1);  % Initialize with the first data point

for i = 2:n
    term = 1;
    for j = 1:i-1
        term = term * (t - x(j)) / (x(i) - x(j));
    end
    result = result + term * y(i);
end

disp(result);
```

This code calculates the interpolated value at `t = 16` using Newton's divided difference formula for the given data points. It iteratively builds up the interpolation result based on the differences between data points.