1RB1RC_1LC1RE_1LD0LB_1RE1LC_1LE0RF_---1RA

1RB1RC_1LC1RE_1LD0LB_1RE1LC_1LE0RF_---1RA (bbch)

Current second longest running BB(6) TM discovered by @racheline on 25 Nov 2024 (Discord Link). It runs for over $10\uparrow \uparrow 7$ steps. It is a halting shift overflow counter.

Analysis by racheline

a_1 = (2^179+1)/3+179
a_2 = (2^a_1+1)/3+a_1
a_3 = (2^a_2+1)/3+a_2
a_4 = (2^a_3+1)/3+a_3-1
a_5 = (2^a_4+1)/3+a_4

the counters after overflow:
(10)^17 11 (10)^5 11 (10)^3 11 (10)^2 1111
(10)^513 11 (10)^17 11 (10)^5 11 (10)^3 11 10 1111
(10)^(2^179+1) 11 (10)^513 11 (10)^17 11 (10)^5 11 (10)^4 1111
(10)^(2^a_1+1) 11 (10)^(2^179+1) 11 (10)^513 11 (10)^17 11 (10)^5 11 (10)^3 1111
(10)^(2^a_2+1) 11 (10)^(2^a_1+1) 11 (10)^(2^179+1) 11 (10)^513 11 (10)^17 11 (10)^5 11 (10)^3 11
(10)^(2^a_3+1) 11 (10)^(2^a_2+1) 11 (10)^(2^a_1+1) 11 (10)^(2^179+1) 11 (10)^513 11 (10)^17 11 (10)^5 11 (10)^2 11
(10)^(2^a_4+1) 11 (10)^(2^a_3+1) 11 (10)^(2^a_2+1) 11 (10)^(2^a_1+1) 11 (10)^(2^179+1) 11 (10)^513 11 (10)^17 11 (10)^4 111111 10 11

halt at roughly 2^a_5 ≈ 2^2^2^2^2^(2^179/3) ≈ 10^10^10^10^10^10^52.8