Edit in JSFiddle

angular.module('demoNgRepeat', [])
.controller('SpecialPropsCtrl', ['$scope', function ($scope) {
  $scope.letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'];
}])

<div ng-app="demoNgRepeat" ng-controller="SpecialPropsCtrl">
    <ul>
      <li ng-repeat="letter in letters" 
        ng-class="{'middleEven' : $middle && $even}">
      {{$index + 1 }} - {{letter}}
      </li>
    </ul>
</div>

.middleEven {
    color : blue;
}