PhpSpreadsheet/tests/data/Shared/Date/TimestampToExcel1904.php

<?php

// Excel DateTimeStamp  Result
return [
    [
        1462,
        -1956528000,
    ],
    [
        1463,
        -1956441600,
    ],
    [
        22269,
        -158803200,
    ],
    [
        25569,
        126316800,
    ],
    [
        30292,
        534384000,
    ],
    [
        39611,
        1339545600,
    ],
];