using System;
public class Test
{
public static void Main()
{
PrintPyramid(4);
}
public static void PrintPyramid(int n)
{
var i = 0;
while (n > 0)
{
Console.Write(++i);
if (IsTriangularNumber(i))
{
Console.Write(Environment.NewLine);
n--;
}
else
{
Console.Write(" ");
}
}
}
public static bool IsTriangularNumber(int i)
{
var n = (int)Math.Sqrt(i*2);
return n*(n + 1) / 2 == i;
}
}
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