Consider the sequence $$1, 7, 8, 49, 50, 56, 57, 343, \ldots$$ which consists of sums of distinct powers of $7$, that is, $7^0$, $7^1$, $7^0 + 7^1$, $7^2$, $\ldots$ in increasing order. At what position will $16856$ occur in this sequence?

Let's think step by step and output the final answer within \boxed{}.
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