CPOJ 太陽神-NOIP十連測-4-3

題面 l c m ( a , b ) > n lcm(a,b)>n lcm(a,b)>n的難求,考慮求 l c m ≤ n lcm\leq n lcm≤n的 ∑ a ∑ b [ a b g c d ( a , b ) ≤ n ] = ∑ g ∑ a ∑ b [ a b ≤ n g ] = ∑ g f n g \begin{array}{l} \sum_a \sum_b[\frac{ab

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