A332970 Colombian palindromes.
1, 3, 5, 7, 9, 121, 222, 323, 424, 525, 626, 727, 828, 929, 1111, 2112, 3113, 4114, 5115, 6116, 7117, 8118, 9119, 10401, 11211, 12921, 13731, 14541, 15351, 16161, 18881, 19691, 20402, 21212, 22922, 23732, 24542, 25352, 26162, 28882, 29692, 30403, 31213, 32923
Offset: 1
Examples
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. 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.
Links
- Shyam Sunder Gupta, On Some Marvellous Numbers of Kaprekar, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 9, 275-315.
- Wikipedia, Self number or Colombian number
- Wikipedia, Palindromic number
- Index to sequences related to Colombian numbers
- Index to sequences related to palindromes
Crossrefs
Programs
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Mathematica
n = 33000; Select[Complement[Range[n], Union @ Table[Plus @@ IntegerDigits[k] + k, {k, 1, n}]], PalindromeQ] (* Amiram Eldar, Mar 04 2020 *)
Extensions
More terms from Amiram Eldar, Mar 04 2020
Comments