Prospective solvers are advised to review the Digits puzzle before attempting to solve this one.
{2}
{53} {59} {61}
{71} {131} {157}
{223} {277} {617} {641}
{1613} {1721} {2029} {2521}
The numbers above are the prime number locations for the 15 digits of the true cache coordinates but they're not in the correct order. To determine the correct order you'll need to look all the other prime locations from {2} through {2521} and catalog the digits at those locations. Here's what the first row of your catalog will look like, you'll need to fill in the remaining 14 rows.
| # |
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
| 1 |
509 |
5 |
13 |
{2} |
23 |
3 |
31 |
37 |
41 |
73 |