using System;

using System.Linq;  

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

        var jan1 = new DateTime(DateTime.Today.Year , 1, 1);

//beware different cultures, see other answers

var startOfFirstWeek = jan1.AddDays(1 - (int)(jan1.DayOfWeek));

var weeks=

    Enumerable

        .Range(0,54)

        .Select(i => new {

            weekStart = startOfFirstWeek.AddDays(i * 7)

        })

        .TakeWhile(x => x.weekStart.Year <= jan1.Year)

        .Select(x => new {

            x.weekStart,

            weekFinish=x.weekStart.AddDays(4)

        })

        .SkipWhile(x => x.weekFinish < jan1.AddDays(1) )

        .Select((x,i) => new {

            WeekStart = x.weekStart.ToString("dd/MM/yyyy"),

            WeekFinish = x.weekFinish.ToString("dd/MM/yyyy"),

            weekNum=i+1

        });

        foreach(var week in weeks) {

        Console.WriteLine(week);

        }

    }

}