title: Sum Subsets Set Formed First N Natural Numbers
signature: function sum_subsets_set_formed_first_n_natural_numbers(n)
test_code: 
  
  -- SOLUTION CODE
  -- ============================================
  PLACEHOLDER_CODE_BODY
  
  -- TESTING CODE 
  -- ============================================
  function isCorrect(actual, expected)
      if type(expected) ~= type(actual) then
          return false
      end
      
      if type(expected) == 'table' then
          for k,v_expected in pairs(expected) do
              
              if actual[k] == nil then
                  return false
              end
              local v_actual = actual[k]
              if not isCorrect(v_actual, v_expected) then
                  return false
              end
              actual[k]=nil
          end
      
          if next(actual) then 
              return false
          end
          return true
      else
          return actual == expected
      end
  end
  
  function validateSolution(actual, expected)
      return math.abs(actual - expected) < 1e-09
  end
  
  function driver(n, expected)
      local exec_result;
      local status, error_msg = pcall(function () 
          exec_result=PLACEHOLDER_FN_NAME(n) 
      end)
      if status then
          if validateSolution(exec_result,expected) then
              return "PASSED"
          end
          return "FAILED"
      else
          return string.format("ERROR=%s",string.gsub(error_msg,".*:[%d]+: ",""))
      end
  end
      
  function main()
      result = driver(26, 11777605632.0)
      print(string.format("TEST-0...%s",result))
  
      result = driver(35, 10823317585920.0)
      print(string.format("TEST-1...%s",result))
  
      result = driver(34, 5111011082240.0)
      print(string.format("TEST-2...%s",result))
  
      result = driver(22, 530579456.0)
      print(string.format("TEST-3...%s",result))
  
      result = driver(3, 24.0)
      print(string.format("TEST-4...%s",result))
  
      result = driver(25, 5452595200.0)
      print(string.format("TEST-5...%s",result))
  
      result = driver(22, 530579456.0)
      print(string.format("TEST-6...%s",result))
  
  end
  
  main()
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 ) );
  }