Enumerable.Range
https://dotblogs.com.tw/rainmaker/2013/04/24/102208
// Generate a sequence of integers from 1 to 10
// and then select their squares.
IEnumerable<int> squares = Enumerable.Range(1, 10).Select(x => x * x);
foreach (int num in squares)
{
Console.WriteLine(num);
}
/*
This code produces the following output:
1
4
9
16
25
36
49
64
81
100
*/
https://docs.microsoft.com/zh-cn/dotnet/api/system.linq.enumerable.range?view=netframework-4.7.2