The infinite sequence $S=\{s_1,s_2,s_3,\ldots\}$ is defined by $s_1=7$ and $s_n=7^{s_{n-1}}$ for each integer $n>1$. What is the remainder when $s_{100}$ is divided by $5$?
Question:
The infinite sequence $S=\{s_1,s_2,s_3,\ldots\}$ is defined by $s_1=7$ and $s_n=7^{s_{n-1}}$ for each integer $n>1$. What is the remainder when $s_{100}$ is divided by $5$?
Answer:
Let's think step by step.

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The infinite sequence $S=\{s_1,s_2,s_3,\ldots\}$ is defined by $s_1=7$ and $s_n=7^{s_{n-1}}$ for each integer $n>1$. What is the remainder when $s_{100}$ is divided by $5$?
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