Skelet 17
1LB---_0RC1LE_0RD1RC_1LA1RB_0LB0LA
(bbch)
Skelet #17 was one of the last holdouts in BB(5).
A full proof of its nonhalting by chxu can be found here: https://chrisxudoesmath.com/papers/skelet17.pdf
Adapting the above, a formal proof of its nonhalting by mxdys can be found here: https://github.com/ccz181078/Coq-BB5/blob/main/Skelet17.md
There was also an analysis by savask: https://docs.bbchallenge.org/other/skelet17_savasks_analysis.pdf
TM Behavior
S can be simulated with the following rules:
A(a0, a1, ..., an)=1 (10)^a0 1 (10)^a1 ... 1 (10)^an