This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A386909 #10 Aug 10 2025 11:55:23 %S A386909 0,6,16,34,64,114,196,334,564,946,1584,2646,4416,7366,12284 %N 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). %C A386909 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). %H A386909 Scott Aaronson, <a href="https://scottaaronson.blog/?p=8088">BusyBeaver(5) is now known to be 47,176,870</a>, Shtetl-Optimized, 2024. %H A386909 Wikipedia, <a href="https://en.wikipedia.org/wiki/Busy_beaver">Busy beaver</a>. %H A386909 <a href="/index/Br#beaver">Index entries for sequences related to Busy Beaver problem</a> %t A386909 NestWhileList[(5*# + If[Mod[#, 3] == 0, 18, 22])/3 &, 0, Mod[#, 3] < 2 &] %Y A386909 Cf. A060843. %K A386909 nonn,fini,full,easy %O A386909 0,2 %A A386909 _Paolo Xausa_, Aug 07 2025