n波那契

        public static double[] Tribonacci(double[] signature, int n)
        {
            int head = signature.Length;
            int rest = n - head;
            double[] result = new double[n];
            if (n == 0)
            {
                return result;
            }
            if (n < head)
            {
                for (int i = 0; i < n; i++)
                {
                    result[i] = signature[i];
                }
                return result;
            }

            for (int i = 0; i < head; i++)
            {
                result[i] = signature[i];
            }

            for (int i = head; i < n; i++)
            {
                double item = 0;
                for (int j = 0; j < head; j++)
                {
                    item += result[i-(j + 1)];
                }
                result[i] = item;
            }

            return result;
        }