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 A043030 #19 Aug 27 2021 02:52:23
%S A043030 3,30,246,255,264,273,282,291,300,309,318,2190,2280,2370,2460,2550,
%T A043030 2640,2730,2820,2910,19686,19767,19848,19929,20010,20091,20172,20253,
%U A043030 20334,20424,20505,20586,20667,20748,20829,20910
%N A043030 Base-9 palindromes that start with 3.
%H A043030 Robert P. P. McKone, <a href="/A043030/b043030.txt">Table of n, a(n) for n = 1..911</a>
%t A043030 okQ[n_] := Module[{idn = IntegerDigits[n, 9]}, First[idn] == 3 && FromDigits[IntegerDigits[n, 9]] == FromDigits[Reverse[idn]]]; Select[Range[20910], okQ] (* _Robert P. P. McKone_, Aug 22 2021, after _Harvey P. Dale_ in A043038 *)
%Y A043030 Cf. A007095, A029955, A043074.
%Y A043030 Cf. A043038.
%K A043030 nonn,base
%O A043030 1,1
%A A043030 _Clark Kimberling_