Solution.oddNumbers(int, int)': not all code paths return a value, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
namespace justtocheck
{
    class Solution
    {

/*
     * Complete the function below.
     */
        static int[] oddNumbers(int l, int r)
        {

//int i = 0;
            for (int i = 0; i <= 5; i++)
                if (i % 2 != 0)

{
                    Console.WriteLine(i);
                }
            Console.ReadLine();

}

static void Main(String[] args)
        {
            string fileName = System.Environment.GetEnvironmentVariable("OUTPUT_PATH");
            TextWriter tw = new StreamWriter(@fileName, true);
            int[] res;
            int _l;
            _l = Convert.ToInt32(Console.ReadLine());

int _r;
            _r = Convert.ToInt32(Console.ReadLine());

res = oddNumbers(_l, _r);
            for (int res_i = 0; res_i < res.Length; res_i++)
            {
                tw.WriteLine(res[res_i]);
            }

tw.Flush();
            tw.Close();
        }
    }
}

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Compilation time: 0,12 s