Why does the pattern start at 11?

Because the printed value is (9 + i + j). On the first row i=1 and j=1, so 9+1+1 = 11.

Can I start from a different base number?

Yes. Replace 9 with a different base value. The first number becomes (base + 1 + 1).

What is the time complexity?

O(n^2) for n rows because the total printed elements are 1+2+...+n.

Increasing Number Triangle Starting from 11 in C#

Beginner

⏱️ 6 min read

📚 Updated: Aug 2025

🎯 2 Code Examples

Nested Loops

Increasing number triangle output starting from 11 in C# programming

What You’ll Learn

How to print a triangle where each row prints values computed from the row and column indices using 9 + i + j.

⭐ Pattern Output

For rows = 5, the pattern looks like this:

Output

11
12 13
13 14 15
14 15 16 17
15 16 17 18 19

Complete C# Program

This matches the reference program: for each row i, print j = 1..i values of (9 + i + j).

using System;

namespace MyApp
{
    class Program
    {
        static void Main(string[] args)
        {
            int i, j;

            for (i = 1; i <= 5; i++)
            {
                for (j = 1; j <= i; j++)
                    Console.Write((9 + i + j) + " ");
                Console.WriteLine();
            }
        }
    }
}

Variation — Custom base and rows

Let the user choose rows and the base value instead of hardcoding 9:

using System;

namespace MyApp
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.Write("Enter rows: ");
            int rows = Convert.ToInt32(Console.ReadLine());
            Console.Write("Enter base: ");
            int baseVal = Convert.ToInt32(Console.ReadLine());
            if (rows < 1) return;

            for (int i = 1; i <= rows; i++)
            {
                for (int j = 1; j <= i; j++)
                    Console.Write((baseVal + i + j) + " ");
                Console.WriteLine();
            }
        }
    }
}