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 A246564 #32 Jul 20 2021 17:22:36 %S A246564 1,0,9,2,0,2,5,3,3,0,7,8,5,6,6,7,8,3,1,0,1,7,8,8,7,8,6,2,4,0,9,8,0,3, %T A246564 0,3,5,6,7,0,6,5,2,0,1,0,7,5,3,0,2,9,5,8,3,6,8,7,0,0,7,3,7,3,0,8,4,0, %U A246564 8,0,7,6,8,0,3,0,6,7,1,0,7,7,2,8,5,7,9,7,3,0,0,9,3,6,6,3,4,2,1,0,5,9,8,8,6 %N A246564 The n-th least-significant decimal digit of n^^n (in _Don Knuth_'s up-arrow notation). %C A246564 This sequence was inspired by the 41st Wohascum County problem. %C A246564 The distribution of the first 500 terms beginning with 0: 101, 43, 40, 42, 29, 49, 43, 53, 58, 42. %C A246564 The distribution does not conform to Benford's / Zipf's law, but seems to be evenly distributed once multiples of ten are excluded. %D A246564 George T. Gilbert, Mark I. Krusemeyer and Loren C. Larson, The Wohascum County Problem Book, The Mathematical Association of America, Dolciani Mathematical Expositions No. 14, 1993, problem 41 "What is the fifth digit from the end (the ten thousands digit) of the number 5^5^5^5^5?", page 11 and solution on page 76. %D A246564 Ilan Vardi, "Computational Recreations in Mathematica," Addison-Wesley Publishing Co., Redwood City, CA, 1991, pages 226-229. %H A246564 Robert G. Wilson v, <a href="/A246564/b246564.txt">Table of n, a(n) for n = 1..1000</a> %H A246564 Robert P. Munafo, <a href="http://www.mrob.com/pub/math/seq-a094358.html">Sequence A094358, 2^^N = 1 mod N</a>. %H A246564 Robert P. Munafo, <a href="http://mrob.com/pub/math/hyper4.html">Hyper4 Iterated Exponential Function</a>. %H A246564 Robert G. Wilson v, <a href="/A133612/a133612_2.txt">Mathematica coding for "SuperPowerMod" from Vardi</a>. %H A246564 Wikipedia, <a href="http://en.wikipedia.org/wiki/Knuth's_up-arrow_notation">Knuth's up-arrow notation</a>. %H A246564 <a href="/index/Be#Benford">Index entries for sequences related to Benford's law</a> %F A246564 if n (mod 10) == 0 then a(n) = 0. %t A246564 (* first load "SuperPowerMod" from Vardi, see link above, and then *) f[n_] := Quotient[ SuperPowerMod[ n, n, 10^n], 10^(n - 1)]; Array[f, 105] %Y A246564 Cf. A241293, A241299, A244059. %K A246564 nonn,base %O A246564 1,3 %A A246564 _Robert G. Wilson v_, Aug 30 2014