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  1. #include<iostream>
  2. #include<cmath>
  3. double binpow(double x, int n) {
  4.     while (--n) 
  5.         x *= x;
  6.     return x;
  7. }
  8. int main() {
  9.     double a, s = 0;
  10.     int n;
  11.     std::cin >> n >> a;
  12.     for (int i = 1; i <= n; i++) 
  13.         s += i * binpow(a, i);
  14.     std::cout << std::abs(s) << std::endl;
  15.  
  16.     return 0;
  17. }
Success #stdin #stdout 0s 2988KB
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https://ideone.com/Uda7EZ
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
secret

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