public function dataProviderForSquareNumber() { return [[-1, []], [0, []], [1, [0]], [2, [0, 1]], [3, [0, 1, 4]], [20, [0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169, 196, 225, 256, 289, 324, 361]]]; }