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 A002140 #19 Oct 14 2023 23:43:34
%S A002140 0,1,821,7812,48361,52187,639972,345328,2517902,9692874,1,17178491,
%T A002140 80813853,71584726,405314501,573958071,654534862,376833014,230022216,
%U A002140 937178398,821,1458801081,8887534942,7445284043,4241746854,5265153016,6710181308,30235306401
%N A002140 7th powers written backwards.
%H A002140 Alois P. Heinz, <a href="/A002140/b002140.txt">Table of n, a(n) for n = 0..10000</a>
%p A002140 a:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||(n^7)):
%p A002140 seq(a(n), n=0..50); # _Alois P. Heinz_, Apr 09 2015
%t A002140 FromDigits[Reverse[IntegerDigits[#]]]&/@(Range[0,25]^7) (* _Harvey P. Dale_, Dec 29 2010 *)
%K A002140 nonn,base,look
%O A002140 0,3
%A A002140 _N. J. A. Sloane_