Decoding strange date format

Is there a non-macro function which could decode this?

Column A --- Column B
62171 --- 1.1.1753
136173 --- 13.8.1955
136174 --- 14.8.1955
136205 --- 14.9.1955
136571 ---14.9.1956

The numbers in Column A are some sort of integers which represent the dates in Column B. I did not decode those example days by myself, but by using an external program (it's a game database editor). I can see that +1 one day in Column B = +1 in the Column A, however I fail to decode the whole formula. I've extracted the values from the database via that editor, but they could be exported only in the format in Column A and I would like to convert them via a function to the Column B format (and then to current age based on the date).

Could you please tell me, how to do that?