pr15

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplicationList
{
    class Program
    {
        static IEnumerable<long> BuildLatticeRow(int size)
        {
            if (size == 0)
            {
                yield return 1;
                yield break;
            }

            var accumulator = 0L;
            foreach (var element in BuildLatticeRow(size - 1))
            {
                accumulator += element;
                yield return accumulator;
            }
            yield return accumulator * 2;
        }

        static void Main(string[] args)
        {
            var latticeRow = BuildLatticeRow(int.Parse(args[0]));

            Console.WriteLine(latticeRow.Last());
            Console.ReadKey();
        }
    }
}

ProgramAlternateVersion.cs

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplicationList
{
    class Program
    {
        static IEnumerable<long> BuildLatticeRow(int size)
        {
            if (size == 0)
            {
                yield return 1;
            }
            else
            {
                var accumulator = 0L;
                foreach (var element in BuildLatticeRow(size - 1))
                {
                    accumulator += element;
                    yield return accumulator;
                }
                yield return accumulator * 2;
            }
        }

        static void Main(string[] args)
        {
            var latticeRow = BuildLatticeRow(int.Parse(args[0]));

            Console.WriteLine(latticeRow.Last());
            Console.ReadKey();
        }
    }
}