posetcay:
The only reason why black could live without seki was because white answer at A18 was a mistake. If white answers C18 at E19, seki is the best black can do. Updated the problem accordingly.

kgcsabi:
The R18-T18-P19-R19-S18-T17-T19-S19-R19 sequence (mentioned also in the review) results in life but other sequences that end up with seki are also accepted.

kgcsabi:
Wondering why seki is accepted when life is achievable.