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 A068665 #13 Oct 25 2019 20:12:16
%S A068665 3,6,66,858,6006,66066,858858,222444222,444888444,21354645312,
%T A068665 21375999957312,211643775577346112,211432343445544343234112,
%U A068665 21354666687999978666645312,211432554877887788778455234112,211221333755564778877465557333122112
%N A068665 a(1) = 3; a(n) = smallest palindromic multiple of a(n-1).
%H A068665 Giovanni Resta, <a href="/A068665/b068665.txt">Table of n, a(n) for n = 1..19</a>
%t A068665 a[1] = 3; a[n_] := a[n] = Block[{k = 2}, While[k*a[n - 1] != ToExpression[ StringReverse[ ToString[k*a[n - 1]]]], k++ ]; k*a[n - 1]]; Table[a[n], {n, 1, 16}]
%t A068665 nxt[n_]:=Module[{k=2},While[k*n!=IntegerReverse[k*n],k++];k*n]; NestList[ nxt,3,15] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Sep 14 2016 *)
%Y A068665 Cf. A068664, A068666, A068667, A068668, A070069, A068971, A068972, A068973, A068974, A083149.
%K A068665 nonn,base
%O A068665 1,1
%A A068665 _Amarnath Murthy_, Mar 01 2002
%E A068665 More terms from _David W. Wilson_; edited by _Patrick De Geest_, Mar 30 2002
%E A068665 a(16) from _Giovanni Resta_, Sep 22 2019