C# Nilakantha级数逼近PI算法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(GetPAI(100));
            Console.Read();
        }

        //Nilakantha级数逼近PI
        public static double GetPAI(int n)
        {
            double pi = 0;
            double s = 0;
            for (int i = 2; i < 2 * n;)
            {
                s = s + Math.Pow(-1, i / 2 + 1) / (i * (i + 1) * (i + 2));
                i += 2;
            }
            pi = 3 + s * 4;
            return pi;
        }
    }
}