static void Main(string[] args)
{
do
{
int n = SoNguyen.NhapSoNguyenDuong("Nhap n = ");
if (TinhToan.ktdang2k(n))
{
Console.Write(n + " co dang 3^k");
}
else
{
Console.Write(n + " khong co dang 3^k");
}
} while (SoNguyen.NhapSoNguyen("\nTiep tuc (1.Tiep, 0.Khong)?") != 0);
}