Let be the largest integer such that divides . Let be the largest integer such that divides . Let be the largest integer such that divides Find the largest integer such that divides .
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To solve this, we will use the function N ( m , n ) = largest integer x such that m x divides n ! which is well-known to have the properties p prime ⟹ N ( p , n ) = k = 1 ∑ ∞ ⌊ p k n ⌋ N ( m k , n ) = ⌊ k 1 N ( m , n ) ⌋ N ( lcm { m 1 , m 2 , … , m k } , n ) = min { N ( m 1 , n ) , N ( m 2 , n ) , … , N ( m k , n ) } }
Turning toward the problem at hand, p q r = N ( 2 0 1 3 , 2 0 1 3 ) = N ( 3 × 1 1 × 6 1 , 2 0 1 3 ) = min { N ( 3 , 2 0 1 3 ) , N ( 1 1 , 2 0 1 3 ) , N ( 6 1 , 2 0 1 3 ) } = N ( 6 1 , 2 0 1 3 ) = 3 3 = N ( 2 0 1 4 , 2 0 1 4 ) = N ( 2 × 1 9 × 5 3 , 2 0 1 4 ) = min { N ( 2 , 2 0 1 4 ) , N ( 1 9 , 2 0 1 4 ) , N ( 5 3 , 2 0 1 4 ) } = N ( 5 3 , 2 0 1 4 ) = 3 8 = N ( 2 0 1 5 , 2 0 1 5 ) = N ( 5 × 1 3 × 3 1 , 2 0 1 5 ) = min { N ( 5 , 2 0 1 5 ) , N ( 1 3 , 2 0 1 5 ) , N ( 3 1 , 2 0 1 5 ) } = N ( 3 1 , 2 0 1 5 ) = 6 5 + 2 = 6 7
so that N ( ( p + 1 ) ( q − 2 ) ( r + 3 ) , 2 0 1 6 ) = N ( 2 4 × 3 2 × 5 × 7 × 1 7 , 2 0 1 6 ) = min { ⌊ 4 1 N ( 2 , 2 0 1 6 ) ⌋ , ⌊ 2 1 N ( 3 , 2 0 1 6 ) ⌋ , N ( 5 , 2 0 1 6 ) , N ( 7 , 2 0 1 6 ) , N ( 1 7 , 2 0 1 6 ) } = min { ⌊ 4 1 N ( 2 , 2 0 1 6 ) ⌋ , ⌊ 2 1 N ( 3 , 2 0 1 6 ) ⌋ , N ( 1 7 , 2 0 1 6 ) } = min { 5 0 2 , 5 0 2 , 1 2 4 } = 1 2 4