PhpSpreadsheet/tests/data/ColumnString.php

<?php

return [
    [
        1,
        'A',
    ],
    [
        26,
        'Z',
    ],
    [
        27,
        'AA',
    ],
    [
        28,
        'AB',
    ],
    [
        52,
        'AZ',
    ],
    [
        53,
        'BA',
    ],
    [
        78,
        'BZ',
    ],
    [
        79,
        'CA',
    ],
    [
        256,
        'IV',
    ],
    [
        702,
        'ZZ',
    ],
    [
        703,
        'AAA',
    ],
    [
        1379,
        'BAA',
    ],
];