Yes, you can use the regex rule in Lumen's validation to allow numbers preceded by 0 as integers. Here's an example:
$request->validate([
'number' => ['required', 'regex:/^[0-9]+$/'],
]);
This will validate that the number parameter is required and contains only digits (0-9). The regex rule uses a regular expression to match the pattern. The ^ and $ characters indicate the start and end of the string, respectively. The + character means one or more occurrences of the preceding character or group (in this case, digits).
With this validation rule, numbers like 01, 02, and 03 will be considered as integers.