Every 7th element in the Fibonacci sequence is divisible by the number 13. This is a known mathematical property of the Fibonacci sequence, where every 7th Fibonacci number is divisible by 13. This can be summarized as: For any positive integer kkk, 131313 divides F7kF_{7k}F7k, where FnF_nFn is the nth Fibonacci number. This result is well documented and provable using modular arithmetic and properties of the Fibonacci sequence. Hence, the answer is 13.
