Count of strings formed using a, b and c with given constraints

 

Given a length n, count the number of strings of length n that can be made using ‘a’, ‘b’ and ‘c’ with at-most one ‘b’ and two ‘c’s allowed.

Input:

The first line of input contains an integer T denoting the number of test cases. Then T test cases follow. The first line of each test case contains an integer N denoting the length of the string.

Output:

Output the count of the strings that can be formed under the given constraint.

Constraints:

1<= T <=100

1<= N <=1000

Example:

Input:

2

1

3

Output:

3

19

#include <iostream>
using namespace std;

int main() {
  int k;
  cin>>k;
  while(k--)
  {
      int n;
      cin>>n;
      int sol=(n*(n-1)*(n+1))/2+2*n+1;
      cout<<sol<<"\n";
      
  }

  return 0;
}

 

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