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 A002239 #15 Oct 14 2023 16:32:59
%S A002239 0,1,215,38691,441262,5213591,69677001,70635304,827712431,984024783,1,
%T A002239 1967497532,2530879515,37399440601,48764016602,57395334483,
%U A002239 63767491786,794678785811,863092953891,977796786223,215,185640082497,2977129627021,3641662511081,4220457081462
%N A002239 9th powers written backwards.
%H A002239 Alois P. Heinz, <a href="/A002239/b002239.txt">Table of n, a(n) for n = 0..10000</a>
%p A002239 a:= n-> (s-> parse(cat(s[-i]$i=1..length(s))))(""||(n^9)):
%p A002239 seq(a(n), n=0..50); # _Alois P. Heinz_, Apr 09 2015
%Y A002239 Cf. A001017.
%K A002239 nonn,base,look
%O A002239 0,3
%A A002239 _N. J. A. Sloane_