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 A325631 #20 Jul 19 2025 00:40:46 %S A325631 0,1,2,3,4,5,4,5,6,7,8,9,8,9,10,11,12,13,12,13,14,15,14,13,14,15,16, %T A325631 15,16,17,16,15,16,17,18,17,16,15,16,17,18,19,20,19,18,19,20,19,20,21, %U A325631 22,23,24,23,22,23,22,23,22,21,20,19,18,19,18,17,18,19,20 %N A325631 Langton's ant on an elongated triangular tiling: number of black cells after n moves of the ant when starting on a square and initially looking towards one of the edges where that square meets one of the neighboring triangles. %C A325631 First differs from A276073 at n = 22. %C A325631 On a white square, turn 90 degrees right, flip the color of the tile, then move forward one unit. %C A325631 On a white triangle, turn 60 degrees right, flip the color of the tile, then move forward one unit. %C A325631 On a black square, turn 90 degrees left, flip the color of the tile, then move forward one unit. %C A325631 On a black triangle, turn 60 degrees left, flip the color of the tile, then move forward one unit. %H A325631 Jinyuan Wang, <a href="/A325631/b325631.txt">Table of n, a(n) for n = 0..2000</a> %H A325631 Felix Fröhlich, <a href="/A325631/a325631.pdf">Illustration of iterations 0-50 of the ant</a>, 2019. %H A325631 Wikipedia, <a href="https://en.wikipedia.org/wiki/Elongated_triangular_tiling">Elongated triangular tiling</a> %H A325631 Wikipedia, <a href="https://en.wikipedia.org/wiki/Langton%27s_ant">Langton's ant</a> %F A325631 a(n) = a(n-51) + 11 for n >= 1159. - _Jinyuan Wang_, Jul 15 2025 %e A325631 See illustrations in Fröhlich, 2019. %Y A325631 Cf. A255938, A269757, A308590, A308937, A308973, A326167, A326352, A309064, A309166, A309241, A309279, A309293. %K A325631 nonn %O A325631 0,3 %A A325631 _Felix Fröhlich_, Sep 07 2019 %E A325631 More terms from _Jinyuan Wang_, Jul 15 2025