EDIT: "Each tile is 256 pixels square and the number of tiles across at each zoom level is given by this formula: Math.pow(2, zoom)"; ops I missed the word "across" :)
How did you come up with that number? The sum loop that follows reports 524287 tiles total.
#include <stdio.h>
#include <math.h>
int main(void)
{
int i;
double tot = 0;
for(i = 0; i <= 18; ++i)
tot += exp2(i);
printf("tot %f\n", tot);
return 0;
}
