It's no longer allowed. A sequence has to be edge to edge with no additional steps/stumbles in between, such as a half loop (actually, I think those are considered combos now)

Yes, that has been true of half loop/Euler into salchow or flip for quite a few years now.

or Hanyu's step straight from his 4T landing into a 3A.

Yes, still a valid sequence.

Just this past year they changed the definition of a sequence to

"A jump sequence consists of 2 (two) jumps of any number of revolutions, beginning with any listed jump, immediately followed by an Axel type jump with a direct step from the landing curve of the first jump to the take-off curve of the Axel jump."

Which means there are even fewer options for valid sequences now. So much for creativity.

It also means that if a skater stumbles between a first and second jump in an intended combination, including a combination with half loop/Euler in the middle, then the jump(s) after the stumble get asterisked and the element gets coded as +Seq in order for the 80% base value to apply to the jump(s) that count(s).

**Executions of jump not counted in Jumps combination or sequence **

If in a jump combination or sequence a skater falls or steps out of a jump and immediately executes another jump(s), the jump(s) after the mistake are not counted, and the call will be the executed jump(s) before the mistake + sequence + the executed jump(s). The jumps after the mistake are marked with an *.

2A(hop)+2A Call: 2A+Seq+2A* 2A+1Eu (fall/step out) +3S Call: 2A+1Eu+Seq+3S*

By doing this all the executed jumps will be visible on the computer screen and it will be easy to follow the requirements of the repetition rule.

The Judges GOE refer to the entire element performed.

Jumps units not fulfilling the definition of Combo/Seq

The jumps are considered in the order of execution. The point where the mistake occurs will be marked with the sign “ + Seq” which results in 80% of the base value for the jumps prior to mistake and asterisk (*) for the jumps after it. E.g.: 3T+2A+Seq.+2T*, 3T+3T+Seq.+2A*, 3T+1Eu+Seq.+2T*