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The value of ⎪ ⎭ ⎪ ⎬ ⎫ ⎪ ⎩ ⎪ ⎨ ⎧ ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + + ∑ = − ∞ → 3 r 3 r 1 tan tan 6 lim 2 n 1 r 1 n is equal to :

1. 1
2. 2
3. 3
4. 6

Correct answer: 3

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