Letter list

Hello,

I'm trying to build a function that displays a list of letters in alphabetical order. It has an input parameter : int t. The output should be:

for t=1: --> output: "a b c d e f g h i j k l m n o p q r s t u v w x y z"
for t=2: --> output: "a b c d e f g h i j k l m n o p q r s t u v w x y z a b c d e f g h i j k l m n o p q r s t u v w x z" -> for the second string letter y is substracted..
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using System;

public class Program {

  public static string LetterList(int t) {
      string output = "";
      output = (char)('a')+" " + output;              
      for (int i = 1; i < 26-t; i++)
       {
        output = output + " " + (char)('a' + i);
       }  

      string output1 = output + " " +(char)('a' +25);
      string output2 = "";   
      for (int j = 0; j<t-0; j++) 
       {  
       output2 +=" "+output1 ;
       }   
     
     return output2;
  }
}

In my case:
for t=1: --> output: " a b c d e f g h i j k l m n o p q r s t u v w x y z"
for t=2: -->output: " a b c d e f g h i j k l m n o p q r s t u v w x z a b c d e f g h i j k l m n o p q r s t u v w x z" so for both strings letter y is substracted and it adds a space in front ....I would appreciate any suggestions. Thanks!