public function dataProviderForHexagonalNumber()
{
return [[-1, []], [0, []], [1, [1 => 1]], [2, [1 => 1, 6]], [3, [1 => 1, 6, 15]], [4, [1 => 1, 6, 15, 28]], [5, [1 => 1, 6, 15, 28, 45]], [6, [1 => 1, 6, 15, 28, 45, 66]], [22, [1 => 1, 6, 15, 28, 45, 66, 91, 120, 153, 190, 231, 276, 325, 378, 435, 496, 561, 630, 703, 780, 861, 946]]];
}