#include <cmath>
#include <iostream>

int main(void)
{
    int levels = 40;
    int xp_for_first_level = 1000;
    int xp_for_last_level = 1000000;

    double B = log((double)xp_for_last_level / xp_for_first_level) / (levels - 1);
    double A = (double)xp_for_first_level / (exp(B) - 1.0);

    for (int i = 1; i <= levels; i++)
    {
        int old_xp = round(A * exp(B * (i - 1)));
        int new_xp = round(A * exp(B * i));
        std::cout << i << " " << (new_xp - old_xp) << std::endl;
    }
}
And the following output:

1 1000          9 4125          17 17012        25 70170        33 289427
2 1193          10 4924         18 20309        26 83768        34 345511
3 1425          11 5878         19 24245        27 100000       35 412462
4 1702          12 7017         20 28943        28 119378       36 492389
5 2031          13 8377         21 34551        29 142510       37 587801
6 2424          14 10000        22 41246        30 170125       38 701704
7 2894          15 11938        23 49239        31 203092       39 837678
8 3455          16 14251        24 58780        32 242446       40 1000000