public void Tribonacci_1()
        {
            var solution = new _1137_NThTribonacciNumber();
            var result   = solution.Tribonacci(4);

            Assert.AreEqual(4, result);
        }
        public void Tribonacci_2()
        {
            var solution = new _1137_NThTribonacciNumber();
            var result   = solution.Tribonacci(25);

            Assert.AreEqual(1389537, result);
        }