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 A175399 #4 Mar 10 2015 02:04:00
%S A175399 0,1,2,3,4,5,6,7,8,9,1,1,1,1,1,1,1,1,1,1,1,2,4,8,1,9,1296,1,
%T A175399 1073741824,25,1,3,9,128,8,4096,1628413597910449,72057594037927936,
%U A175399 221073919720733357899776,1,1,4,1,1296,1073741824,1,1,1
%N A175399 Sequence of resulting numbers after 2nd step of iteration defined in A175398.
%C A175399 See A175398, A175400, A175401, A175402, A175403.
%e A175399 For n = 29: a(29) = 25 because for the number 29 there are 4 steps of defined iteration: {2^9 = 512}, {(5^1)^2 = 25}, {2^5 = 32}, {3^2 = 9}, and the 2nd step of the iteration ends with 25.
%K A175399 nonn
%O A175399 0,3
%A A175399 _Jaroslav Krizek_, May 01 2010