A386909 Iterates of g(x), starting at x = 0 until g(x) == 2 (mod 3), where g(x) = (5*x + 18)/3 if x == 0 (mod 3) and g(x) = (5*x + 22)/3 if x == 1 (mod 3).

0, 6, 16, 34, 64, 114, 196, 334, 564, 946, 1584, 2646, 4416, 7366, 12284

Offset

0,2

Comments

These iterates correspond to the computation carried out by the 5-state Marxen-Buntrock Turing machine, which halts after 47176870 = BB(5) = A060843(5) steps (see Aaronson link).

Links

Table of n, a(n) for n=0..14.

Scott Aaronson, BusyBeaver(5) is now known to be 47,176,870, Shtetl-Optimized, 2024.

Wikipedia, Busy beaver.

Index entries for sequences related to Busy Beaver problem

Mathematica

NestWhileList[(5*# + If[Mod[#, 3] == 0, 18, 22])/3 &, 0, Mod[#, 3] < 2 &]

Crossrefs

Cf. A060843.

Sequence in context: A236773 A131820 A266677 * A083053 A083046 A192749

Adjacent sequences: A386906 A386907 A386908 * A386910 A386911 A386912

Keyword

nonn,fini,full,easy

Author

Paolo Xausa, Aug 07 2025

Status

approved