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 A204714 #12 Feb 16 2025 08:33:16
%S A204714 1,1,1,4,1,4,4,8,27,30,99,12,169,112,330,40,289,306,494,86,399,484,
%T A204714 690,312,1800,624,918,224,783,780,1240,608,1056,952,1540,684
%N A204714 Maximum period of cellular automaton rule 54 in a cyclic universe of width n.
%H A204714 <a href="/index/Ce#cell">Index entries for sequences related to cellular automata</a>
%H A204714 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Rule54.html">Rule 54</a>
%e A204714 For n=8, the initial condition 00011101 yields the evolution
%e A204714 00011101
%e A204714 10100011
%e A204714 01110100
%e A204714 10001110
%e A204714 11010001
%e A204714 00111010
%e A204714 01000111
%e A204714 11101000
%e A204714 00011101
%e A204714 Which is period 8, the maximum possible, so a(8)=8.
%t A204714 f[list_] := -Subtract @@ Flatten[Map[Position[#, #[[-1]]] &, NestWhileList[CellularAutomaton[54], list, Unequal, All], {0}]]; a[n_] := Max[Table[f[IntegerDigits[i, 2, n]], {i, 0, 2^n - 1}]]; Table[a[n], {n, 1, 10}]
%Y A204714 Cf. A071030, A118108
%K A204714 nonn
%O A204714 1,4
%A A204714 _Ben Branman_, Jan 18 2012
%E A204714 a(15)-a(36) from _Lars Blomberg_, Dec 24 2015