1RB0LD_1RC0RF_1LC1LA_0LE1RZ_1LF0RB_0RC0RE

1RB0LD_1RC0RF_1LC1LA_0LE1RZ_1LF0RB_0RC0RE (bbch) is a former BB(6) champion. It was discovered by Pavel Kropitz on 30 May 2022. This TM runs for over 10↑↑15 steps. An improved bound for this TMs runtime was achieved by Shawn Ligocki, using an extended version of tetration: $10\uparrow \uparrow 15.60463<Score<Runtime<10\uparrow \uparrow 15.60466$. See analysis: .

It simulates the following Collatz-like rules, starting at $C(5)$, on tape configurations $C(n)=0^{\mathrm{\infty }}10^{n}110^5\text{C}>0^{\mathrm{\infty }}$:

$$\begin{array}{lll}C(4k)& \to & Halt(\frac{3^{k+3}-11}{2})\\ C(4k+1)& \to & C(\frac{3^{k+3}-11}{2})\\ C(4k+2)& \to & C(\frac{3^{k+3}-11}{2})\\ C(4k+3)& \to & C(\frac{3^{k+3}+1}{2})\\ \end{array}$$