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 A043044 #18 Sep 02 2025 01:45:06
%S A043044 9,99,909,919,929,939,949,959,969,979,989,999,9009,9119,9229,9339,
%T A043044 9449,9559,9669,9779,9889,9999,90009,90109,90209,90309,90409,90509,
%U A043044 90609,90709,90809,90909,91019,91119,91219,91319,91419,91519,91619,91719,91819,91919
%N A043044 Palindromes that start with 9.
%C A043044 Subsequence of A002113 (palindromic numbers). Union of A128375 (palindromic primes starting with a digit 9) and A222729 (palindromic composite numbers starting with a digit 9). - _Jaroslav Krizek_, Mar 12 2013
%H A043044 Jaroslav Krizek, <a href="/A043044/b043044.txt">Table of n, a(n) for n = 1..2222</a>
%t A043044 palQ[n_Integer, base_Integer] := Module[{idn = IntegerDigits[n, base]}, idn == Reverse[idn]]; Select[Range[0, 100000], IntegerDigits[#][[1]] == 9 && palQ[#, 10] &] (* _T. D. Noe_, Mar 12 2013 *)
%t A043044 Select[Range[100000],PalindromeQ[#]&&IntegerDigits[#][[1]]==9&] (* _Harvey P. Dale_, Oct 13 2022 *)
%t A043044 Join[{9},Table[Select[Flatten[Range[9*10^ex+9,10^(ex+1)-1,10]],PalindromeQ],{ex,4}]]//Flatten (* _Harvey P. Dale_, Apr 02 2025 *)
%K A043044 nonn,base,changed
%O A043044 1,1
%A A043044 _Clark Kimberling_