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• $$a \uparrow^1 b = a^b$$
• $$a \uparrow^n 1 = a$$
• $$a \uparrow^n b = a \uparrow^{n-1} (a \uparrow^n (b-1))$$

$$a \uparrow^n b$$ 為 $$a \uparrow\uparrow...\uparrow b$$ 的縮寫（其中 $$\uparrow$$ 有n個，n為正整數）。例如 $$a \uparrow^2 b = a \uparrow\uparrow b$$ 。

## 例子

• $$2 \uparrow 3 = 2^3 = 8$$
• $$5 \uparrow 6 = 5^6 = 15625$$
• $$10 \uparrow 100 = 10^{100} =$$ 古戈爾
• $$3 \uparrow\uparrow 4 = 3 \uparrow 3 \uparrow 3 \uparrow 3 = 3 \uparrow 3 \uparrow 27 = 3^{7625597484987}$$
• $$5 \uparrow\uparrow 3 = 5 \uparrow 5 \uparrow 5 = 5^{5^5}$$
• $$2 \uparrow\uparrow\uparrow 2 = 2 \uparrow\uparrow 2 = 2 \uparrow 2 = 2^2 = 4$$
• $$3 \uparrow\uparrow\uparrow 2 = 3 \uparrow\uparrow 3 = 3 \uparrow 3 \uparrow 3 = 3^{3^3} = 3^{27} = 7625597484987$$
• $$2 \uparrow\uparrow\uparrow 3 = 2 \uparrow\uparrow 2 \uparrow\uparrow 2 = 2 \uparrow\uparrow 4 = 2 \uparrow 2 \uparrow 2 \uparrow 2 = 2 \uparrow 2 \uparrow 4 = 2 \uparrow 16 = 65536$$
• $$3 \uparrow\uparrow\uparrow 3 = 3 \uparrow\uparrow 3 \uparrow\uparrow 3 = 3 \uparrow\uparrow 7625597484987 =$$ 特利特利