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 A325955 #28 Jul 16 2025 17:54:51 %S A325955 0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,2,2,2,1,1,1,0,1,1,1,1,0,0,0,0,0,0,0, %T A325955 0,0,0,1,1,1,1,1,1,1,2,2,2,1,1,1,0,1,1,1,1,0,0,0,0,0,0,0,0,0,0,1,1,1, %U A325955 2,2,2,2,2,2,3,4,4,4,5,5,5,5,5,6,6,6,5 %N A325955 Langton's ant on a three-dimensional grid: number of yellow cells on the grid after n moves of the ant. %C A325955 The ant starts on a completely white grid. %C A325955 Order of operations: turn 90 degrees, change cell color, move forward one unit. %C A325955 The rules governing the movement of the ant and the change of cell colors are shown in the following table: %C A325955 Cell color at | Direction of | Color the cell is %C A325955 start of iteration | 90-degree turn | changed to %C A325955 -------------------------------------------------------- %C A325955 white | right | black %C A325955 black | left | blue %C A325955 blue | up | yellow %C A325955 yellow | down | white %H A325955 Jinyuan Wang, <a href="/A325955/b325955.txt">Table of n, a(n) for n = 0..10000</a> %H A325955 Felix Fröhlich, <a href="/A325953/a325953_2.pdf">Illustration of iterations 0-50 of the ant</a> %H A325955 Wikipedia, <a href="https://en.wikipedia.org/wiki/Langton%27s_ant">Langton's ant</a> %F A325955 a(n) = a(n-28) + 4 for n >= 93504. - _Jinyuan Wang_, Jul 13 2025 %e A325955 See illustration in links. %Y A325955 Cf. A255938, A308563, A325953, A325954. %K A325955 nonn %O A325955 0,17 %A A325955 _Felix Fröhlich_, May 28 2019 %E A325955 a(51)-a(81) from _Charlie Neder_, Jun 06 2019