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 A029969 #35 Aug 11 2024 14:41:30
%S A029969 0,1,2,3,4,5,6,7,8,9,11,323,464,717,858,999,1111,39593,59095,420024,
%T A029969 546645,9046409,9578759,9813189,535505535,564303465,595121595,
%U A029969 5736116375,6758008576,10476867401,11652825611,14203330241
%N A029969 Numbers that are palindromic in bases 10 and 14.
%H A029969 Robert G. Wilson v, <a href="/A029969/b029969.txt">Table of n, a(n) for n = 1..70</a> (first 63 terms from Ray Chandler)
%H A029969 P. De Geest, <a href="https://www.worldofnumbers.com/nobase10.htm">Palindromic numbers beyond base 10</a>
%t A029969 NextPalindrome[n_] := Block[{l = Floor[ Log[10, n] + 1], idn = IntegerDigits[n]}, If[ Union[idn] == {9}, Return[n + 2], If[l < 2, Return[n + 1], If[ FromDigits[ Reverse[ Take[idn, Ceiling[l/2]] ]] FromDigits[ Take[idn, -Ceiling[l/2]]], FromDigits[ Join[ Take[idn, Ceiling[l/2]], Reverse[ Take[idn, Floor[l/2]] ]]], idfhn = FromDigits[ Take[idn, Ceiling[l/2]]] + 1; idp = FromDigits[ Join[ IntegerDigits[idfhn], Drop[ Reverse[ IntegerDigits[idfhn]], Mod[l, 2]] ]]] ]]]; palQ[n_Integer, base_Integer] := Block[{idn = IntegerDigits[n, base]}, idn == Reverse[idn]]; l = {0}; a = 0; Do[a = NextPalindrome[a]; If[ palQ[a, 14], AppendTo[l, a]], {n, 300000}]; l (* _Robert G. Wilson v_, Sep 03 2004 *)
%t A029969 b1=10; b2=14; lst={}; Do[d1=IntegerDigits[n, b1]; d2=IntegerDigits[n, b2]; If[d1==Reverse[d1]&&d2==Reverse[d2], AppendTo[lst, n]], {n, 0, 1000000}]; lst (* _Vincenzo Librandi_, Nov 23 2014 *)
%t A029969 palQ[n_]:=Module[{idn14=IntegerDigits[n,14]},n==IntegerReverse[n]&&idn14==Reverse[idn14]]; Select[Range[10^7],palQ] (* The program uses the IntegerReverse function from Mathematica version 10 *) (* _Harvey P. Dale_, Apr 23 2016 *)
%t A029969 Select[Range[0, 10^5],
%t A029969 PalindromeQ[#] && # == IntegerReverse[#, 14] &] (* _Robert Price_, Nov 09 2019 *)
%o A029969 (Magma) [n: n in [0..10000000] | Intseq(n, 10) eq Reverse(Intseq(n, 10))and Intseq(n, 14) eq Reverse(Intseq(n, 14))]; // _Vincenzo Librandi_, Nov 23 2014
%Y A029969 Cf. A007632, A007633, A029961, A029962, A029963, A029964, A029804, A029965, A029966, A029967, A029968, A029970, A029731, A097855, A099165.
%K A029969 nonn,base
%O A029969 1,3
%A A029969 _Patrick De Geest_