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 A071584 #13 Jul 06 2025 18:52:33
%S A071584 1,7,94,343,1042,70861,946711,345328,1084675,70635304,942574282,
%T A071584 3476237791,10278214831,70401098869,948270322876,3499051657474,
%U A071584 10696503923233,702789315036232,9440197953148261,34137358159889311
%N A071584 Powers of 7 written backwards.
%H A071584 Alois P. Heinz, <a href="/A071584/b071584.txt">Table of n, a(n) for n = 0..1000</a>
%p A071584 a:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||(7^n)):
%p A071584 seq(a(n), n=0..50); # _Alois P. Heinz_, Apr 09 2015
%t A071584 FromDigits[Reverse[IntegerDigits[#]]]&/@(7^Range[0,20]) (* _Harvey P. Dale_, Apr 29 2012 *)
%t A071584 IntegerReverse[7^Range[0,20]] (* _Harvey P. Dale_, Jul 06 2025 *)
%o A071584 (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 A071584 easy,nonn,base
%O A071584 0,2
%A A071584 _Benoit Cloitre_, Jun 01 2002