var FundraiserIDsadd = [];
        FundraiserIDsadd.push(19336);
        FundraiserIDsadd.push(15169);
        FundraiserIDsadd.push(15176);

window.location.href = '@Url.Action("ExportCSV", "Admin", new { FundraiserIDs = FundraiserIDsadd })';

public ActionResult ExportCSV(List<int> FundraiserIDs)
    {
        DO some stuff..
    }