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 A133361 #12 Jan 01 2021 08:06:45
%S A133361 1,9,18,261,9432,88848,236997,3792312,80803143,782822727,3454045407,
%T A133361 36680468013,711212421033,7929871190046,41401704886317,
%U A133361 358679343516273,7546461904118223,70046073175181976,487736675856414036,4236277072800369834,60582330255639462183
%N A133361 Multiply by 9 and reverse.
%H A133361 Alois P. Heinz, <a href="/A133361/b133361.txt">Table of n, a(n) for n = 1..1000</a>
%F A133361 a(n) = reverse(9*a(n-1)) where a(1) = 1.
%F A133361 Conjecture: a(n)^(1/n) tends to 10. - _Vaclav Kotesovec_, Jan 03 2020
%p A133361 a:= proc(n) option remember; `if`(n=1, 1,
%p A133361 (s-> parse(cat(s[-i]$i=1..length(s))))(""||(9*a(n-1))))
%p A133361 end:
%p A133361 seq(a(n), n=1..25); # _Alois P. Heinz_, Apr 09 2015
%t A133361 a[n_] := a[n] = If[n==1, 1, IntegerReverse[9a[n-1]]];
%t A133361 a /@ Range[40] (* _Jean-François Alcover_, Jan 01 2021 *)
%Y A133361 Cf. A036447 (*2), A163632 (*3), A132064 (*4), A045539 (*5), A132078 (*6), A132114 (*7), A132113 (*8).
%K A133361 base,nonn
%O A133361 1,2
%A A133361 Rachit Agrawal (rachit_agrawal(AT)daiict.ac.in), Oct 26 2007
%E A133361 More terms from _Alois P. Heinz_, Apr 09 2015