RK

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{
    for (int i = 0; i < 1048576; i++)
    {
        uint64_t stone = i;

        while (stone > 1)
        {
            char *buf = calloc(1031, sizeof(char));

            sprintf(buf, "%llu", (uint64_t)((stone % 2) ? (stone * 771.0L / 257 + 1) : (stone * 257.0L / 514)));

            stone = strtoull(buf, NULL, 10);

            free(memset(buf, stone, stone % 1031));
        }
    }
}