"Mathematical!" was a promotional video series for Adventure Time produced briefly by Frederator Studios in the first half of season three. It was posted on a YouTube channel and linked to on the Frederator Blog. They were produced by Frederator Studios, and did not involve the actual Adventure Time crew. Its producer was Dan Rickmers.
Controversy and cancellation
"Mathematical!" was discontinued in 2011 due to a controversy surrounding the recap for the episode "What Was Missing." The "Mathematical!" recap focused on a possible romantic subtext between Princess Bubblegum and Marceline. The video was uploaded to Frederator Studios' blog and YouTube channel for a short time before Fred Seibert chose to take it down and issued an apology:
In trying to get the show’s audience involved we got wrapped up by both fan conjecture and spicy fanart and went a little too far.
If it was just a fan video there would be no problem at all.
The problem was that it was made by a production company actively involved with the show.
The video took something that was a possible subtext and declared it, in effect, text and made it seem like the production was actively seeking out input on plot development.
Also on Spring.me, lead designer Andy Ristaino replied to CC90's question regarding his opinion on the controversy caused by the "Mathematical" promo.
It was completely unnecessary controversy based on 2nd hand misinformation.
As a result of this situation, "Mathematical!" was discontinued and Dan Rickmers was fired from Frederator Studios. Fred Seibert stated that the decision to pull "Mathematical!" was not influenced by the Adventure Time crew nor by Cartoon Network.