Răspuns:
n = 10
Explicație pas cu pas:
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ab..x = > a+b+....+x = 13 ;
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a₁+a₂+......+aₙ = 13 ; n ∈ N ; n = ? n = minim ; n > 1
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ab minim = 49 => 4+9 = 13
49 ; 58 ; 67 ; 76 ; 85 ; 94 ; 139 ; 148 ; 157 ; 166 ; 175 ; 184 ; 193;
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49+58 = 107 => 8
49+58+67 = 174 => 12
49+58+67+76 = 250 => 7
49+58+67+76+85 = 335 => 11
49+58+67+76+85+94 = 429 => 15
49+58+67+76+85+94 +139 = 568 => 19
49+58+67+76+85+94 +139+148 = 716 => 14
49+58+67+76+85+94 +139+148+157 = 873 => 18
49+58+67+76+85+94 +139+148+157+166 = 1039 => 13
=> n = 10 (10 numere ''cu ghinion'')