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 A071583 #10 May 15 2017 15:29:03
%S A071583 1,5,52,521,526,5213,52651,52187,526093,5213591,5265679,52182884,
%T A071583 526041442,5213070221,5265153016,52187571503,526098785251,
%U A071583 521354939267,5265627964183,52182368437091,52604613476359,521302851738674
%N A071583 Powers of 5 written backwards.
%H A071583 Alois P. Heinz, <a href="/A071583/b071583.txt">Table of n, a(n) for n = 0..1000</a>
%p A071583 a:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||(5^n)):
%p A071583 seq(a(n), n=0..50); # _Alois P. Heinz_, Apr 09 2015
%t A071583 IntegerReverse/@(5^Range[0,30]) (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, May 15 2017 *)
%o A071583 (PARI) for(i=1,50,n=5^i; s=ceil(log(n)/log(10)); print1(sum(i=0,s,10^(s-i-1)*(floor(n/10^i)-10*floor(n/10^(i+1)))),","))
%K A071583 easy,nonn,base
%O A071583 0,2
%A A071583 _Benoit Cloitre_, Jun 01 2002