retry web requests, with exponential backoff, using functional linq in c#

RetryWebRequests.cs

var labelsPage = Enumerable
    .Range(0, 5) 
    .Select(pageAttempt => 
    {
        Thread.Sleep(2500 * pageAttempt * pageAttempt);
        try
        {
            var labelsAwql = "select LabelId,LabelName,LabelStatus limit 0,100";
            var attemptedlabelsPage = Config.LabelService.query(labelsAwql);

            return attemptedlabelsPage;
        }
        catch (AdWordsApiException e)
        {
            return null;
        }
    })
    .First(page => 
    {
        var nonNullFound = page != null;
        return nonNullFound;
    });