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 A071686 #20 Nov 14 2019 10:45:53
%S A071686 2,4,8,2192,21920,291008,610688,2112256,2131456,2937856,25329664,
%T A071686 230465536,694018048,2344321024,4688642048,2112421888,65012891648,
%U A071686 650128916480,4494196736,63769149440,637691494400,23842827272192,276298064723968,420127895977984,4897795987210240
%N A071686 Smallest solution to gcd(x, Rev(x)) = 2^n.
%H A071686 Giovanni Resta, <a href="/A071686/b071686.txt">Table of n, a(n) for n = 1..32</a>
%F A071686 a(n) = A069554(2^n).
%t A071686 a[n_] := Block[{k = 2^n}, While[GCD[k, FromDigits@ Reverse@ IntegerDigits@ k] != 2^n, k += 2^n]; k]; Array[a, 17] (* _Giovanni Resta_, Nov 14 2019 *)
%Y A071686 Cf. A004086, A055483, A069554, A072005, A072021, A072050.
%K A071686 nonn,base
%O A071686 1,1
%A A071686 _Labos Elemer_, Jun 03 2002
%E A071686 a(22)-a(25) from _Giovanni Resta_, Oct 29 2019