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 A121864 #9 Jul 06 2018 04:46:01 %S A121864 16,50,406,1258008,25465014649108,208080288305986199465852412572946560 %N A121864 See Comments lines for definition. %C A121864 Let "N_b" denote "N read in base b" and let "N" denote "N written in base 10" (as in normal life). The sequence is given by 16, 32_16, (64_32)_16, ((128_64)_32)_16, etc., or in other words %C A121864 ......16....32.....64....128.......etc. %C A121864 ..............16.....32.....64......... %C A121864 .......................16.....32....... %C A121864 ................................16..... %C A121864 where the subscripts are evaluated from the top downwards %C A121864 More precisely, "N_b" means "Take decimal expansion of N and evaluate it as if it were a base-b expansion". %C A121864 The next term is too large to include. %C A121864 A "dungeon" of numbers. %D A121864 David Applegate, Marc LeBrun and N. J. A. Sloane, Descending Dungeons and Iterated Base-Changing, in "The Mathematics of Preference, Choice and Order: Essays in Honor of Peter Fishburn", edited by Steven Brams, William V. Gehrlein and Fred S. Roberts, Springer, 2009, pp. 393-402. %H A121864 David Applegate, Marc LeBrun and N. J. A. Sloane, <a href="https://arxiv.org/abs/math/0611293">Descending Dungeons and Iterated Base-Changing</a>, arXiv:math/0611293 [math.NT], 2006-2007. %H A121864 David Applegate, Marc LeBrun, N. J. A. Sloane, <a href="https://www.jstor.org/stable/40391135">Descending Dungeons, Problem 11286</a>, Amer. Math. Monthly, 116 (2009) 466-467. %e A121864 (64_32)_16 = (6*32 + 4)_16 = 196_16 = 1*256 + 9*16 + 6 = 406. %Y A121864 Cf. A121863, A121263, A121266, A121264, A121265, A121295, A121296, A111050, A121866, A122029, A122030. %K A121864 nonn,base %O A121864 4,1 %A A121864 _N. J. A. Sloane_, Aug 31 2006, corrected Sep 05 2006