7 lines
167 B
Text
7 lines
167 B
Text
module
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theorem sum_of_n (n : Nat) :
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(List.range (n + 1)).sum = n * (n + 1) / 2 := by
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induction n with
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| zero => rfl
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| succ k ih =>
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grind [List.range_succ]
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