Here is the logic : n is number of lines provided by user:
for (int i = 1; i <= n; i++)
{
for (int j = i; j <= 12; j++)
{
Console.Write(" ");
}
for (int k = 1; k <= 2 * i - 1; k++)
{
Console.Write("*" + " ");
}
Console.WriteLine();
}
Console.ReadLine();