Ref: https://www.digital-detective.net/deciphering-seagate-date-codes/
Seagate uses a fiscal year for their calculation which starts on the first Saturday in July (week 1). 1st July 2000 was a Saturday which is Date Code 01011 (or 0111).
For example, the fiscal year 2021 starts on Saturday 4th July 2020 (Date Code 2111) and ends on Friday 2nd July 2021 (Date Code 21527). Date Code 13395 was manufactured on 3rd April 2013 (fiscal year 2013, week 39, day 5).
seagate DATECODE
The DATECODE is either YYWD or YYWWD
Y Year
W Week number (1 or 2 digits)
D Week day
This was originally written for Linux as a Bash script.