Napadlo mě to, ale nevím jak porovnat obsah txtBoxu s tím polem.
int[] x = { 2, 4, 6, 8, 10, 11, 13, 15, 17, 20, 22, 24, 26, 28, 29, 31, 33, 35 };
for (int i = 0; i < 36; i++)
{
if (_[i] == x[i])
}