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 A244059 #23 Feb 16 2025 08:33:22 %S A244059 1,1,6,1,2,1,4,7,6,2,1 %N A244059 Initial digit of the decimal expansion of n^(n^(n^n)) or n^^4 (in Don Knuth's up-arrow notation). %C A244059 This sequence can also be written as (nāā4) in Knuth up-arrow notation. %C A244059 0^^4 = 1 since 0^^k = 1 for even k, 0 for odd k, k >= 0. %C A244059 Conjecture: the distribution of the initial digits obey G. K. Zipf's law. %H A244059 Cut the Knot.org, <a href="http://www.cut-the-knot.org/do_you_know/zipfLaw.shtml">Benford's Law and Zipf's Law</a>, A. Bogomolny, Zipf's Law, Benford's Law from Interactive Mathematics Miscellany and Puzzles. %H A244059 M. E. J. Newman, <a href="http://arxiv.org/abs/cond-mat/0412004">Power laws, Pareto distributions and Zipf's law.</a> %H A244059 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/JoyceSequence.html">Joyce Sequence</a> %H A244059 Wikipedia, <a href="http://en.wikipedia.org/wiki/Knuth's_up-arrow_notation">Knuth's up-arrow notation</a> %H A244059 Wikipedia, <a href="http://en.wikipedia.org/wiki/Zipf's_law">Zipf's law</a> %H A244059 <a href="/index/Be#Benford">Index entries for sequences related to Benford's law</a> %e A244059 a(4)=2 because A241293(1)=2. %o A244059 (PARI) a(n)=digits(n^n^n^n)[1] \\ impractical for large n; _Charles R Greathouse IV_, May 13 2015 %Y A244059 Cf. A241291, A241292, A241293, A241294, A241295, A241296, A241297, A243913, A241299. %Y A244059 Cf. A324220 (number of digits). %K A244059 nonn,base,hard,more %O A244059 0,3 %A A244059 _Robert Munafo_ and _Robert G. Wilson v_, Jun 18 2014