For some reason my #FediPuzzles challenges appear to be getting NSFW responses! I am not entirely sure why, they will always be safe-for-work on my side.
Anyway, today's is just a number sequence so I'm looking forward to some "nice", clean replies.
Remember to use a content warning for your guess, so as not to spoil it for others!
![#FediPuzzles
What is the next number in this sequence?
6, 9, 15, 21, 33, 39, 51, 57, [question mark]
Reply with your answer behind a content warning (to not spoil it for others!), and like this post if you want to be tagged when the answer is revealed in approximately over 24 hours from now!](https://files.mastodon.online/media_attachments/files/115/843/741/939/643/191/original/0845bffe76078ba4.jpg)
