title: Sum Subsets Set Formed First N Natural Numbers
signature: sumSubsetsSetFormedFirstNNaturalNumbers(n) {
test_code: import 'dart:convert';
  
  // SOLUTION CODE
  // ============================================
  PLACEHOLDER_CODE_BODY
  
  // TESTING CODE 
  // ============================================
  bool validateSolution(double actual, double expected){
      return (actual - expected).abs() < 1e-09;
  }
  
  String driver(n, double expected){
      try
      {
          if (validateSolution(PLACEHOLDER_FN_NAME(n), expected)){
              return "PASSED";
          }
          return "FAILED";
      }catch(exception_object){
          return exception_object.runtimeType.toString();
      }
  }
  
  int main() {
  
      print("TEST-0...${driver(
          26, 
          11777605632.0)
      }");
  
      print("TEST-1...${driver(
          35, 
          10823317585920.0)
      }");
  
      print("TEST-2...${driver(
          34, 
          5111011082240.0)
      }");
  
      print("TEST-3...${driver(
          22, 
          530579456.0)
      }");
  
      print("TEST-4...${driver(
          3, 
          24.0)
      }");
  
      print("TEST-5...${driver(
          25, 
          5452595200.0)
      }");
  
      print("TEST-6...${driver(
          22, 
          530579456.0)
      }");
  
      return 0;
  }
source_py: def sum_subsets_set_formed_first_n_natural_numbers(n):
      return (((n * (n + 1)) / 2) * (1 << (n - 1)))
source_cpp: unsigned long long sum_subsets_set_formed_first_n_natural_numbers(int n) {
    return ( n * ( n + 1 ) / 2 ) * ( 1 << ( n - 1 ) );
  }