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 A246605 #9 Sep 17 2014 21:11:09
%S A246605 0,1,2,3,4,5,6,7,8,9,81,512,729,2401,6561,32768,59049,531441,2097152,
%T A246605 4782969,43046721,134217728,387420489,3486784401,31381059609,
%U A246605 282429536481,2541865828329,22876792454961,205891132094649,1853020188851841,16677181699666569,150094635296999121,1350851717672992089,12157665459056928801,109418989131512359209
%N A246605 Numbers n such that n = (digital root of n)^(number of digits of n).
%C A246605 This is a supersequence of A038178. Its finiteness stems from the fact that the number of digits of (digital root(x))^y is less than y, for every y > 21.
%H A246605 Ivan N. Ianakiev, <a href="/A246605/b246605.txt">Table of n, a(n) for n = 0..34</a>
%e A246605 a(10) = 81 = 9^2 = A010888(81)^A055642(81).
%t A246605 lst={0,1,2,3,4,5,6};Do[If[7^n==Mod[7^n,9]^n,AppendTo[lst,7^n]],{n,1,9}];Do[If[8^n==Mod[8^n,9]^n,AppendTo[lst,8^n]],{n,1,9}];Union[Join[lst,Table[9^x,{x,1,21}]]]
%Y A246605 Cf. A010888, A055642, A038178.
%K A246605 base,nonn,fini,full
%O A246605 0,3
%A A246605 _Ivan N. Ianakiev_, Aug 31 2014