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 A332970 #30 Mar 26 2025 08:52:15
%S A332970 1,3,5,7,9,121,222,323,424,525,626,727,828,929,1111,2112,3113,4114,
%T A332970 5115,6116,7117,8118,9119,10401,11211,12921,13731,14541,15351,16161,
%U A332970 18881,19691,20402,21212,22922,23732,24542,25352,26162,28882,29692,30403,31213,32923
%N A332970 Colombian palindromes.
%C A332970 Palindromes that are not the sum of an integer and of the individual digits of this integer (see Wikipedia link).
%H A332970 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_9">On Some Marvellous Numbers of Kaprekar</a>, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 9, 275-315.
%H A332970 Wikipedia, <a href="https://en.wikipedia.org/wiki/Self_number">Self number or Colombian number</a>
%H A332970 Wikipedia, <a href="https://en.wikipedia.org/wiki/Palindromic_number">Palindromic number</a>
%H A332970 <a href="/index/Coi#Colombian">Index to sequences related to Colombian numbers</a>
%H A332970 <a href="/index/Pac#palindromes">Index to sequences related to palindromes</a>
%e A332970 323 is a palindrome that cannot be written as the sum of any other natural number k and the digits of k, hence 323 that is Colombian number in base 10 is a term.
%e A332970 333 is a palindrome but 333 = 324 + 3 + 2 + 4, hence 333 that is not a self number in base 10 is not a term.
%t A332970 n = 33000; Select[Complement[Range[n], Union @ Table[Plus @@ IntegerDigits[k] + k, {k, 1, n}]], PalindromeQ] (* _Amiram Eldar_, Mar 04 2020 *)
%Y A332970 Intersection of A002113 (palindromes) and A003052 (Colombians).
%Y A332970 Complement of A332240 relative to A002113.
%K A332970 nonn,base
%O A332970 1,2
%A A332970 _Bernard Schott_, Mar 04 2020
%E A332970 More terms from _Amiram Eldar_, Mar 04 2020