OFFSET
1,2
COMMENTS
Palindromes that are not the sum of an integer and of the individual digits of this integer (see Wikipedia link).
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
EXAMPLE
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.
MATHEMATICA
n = 33000; Select[Complement[Range[n], Union @ Table[Plus @@ IntegerDigits[k] + k, {k, 1, n}]], PalindromeQ] (* Amiram Eldar, Mar 04 2020 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Bernard Schott, Mar 04 2020
EXTENSIONS
More terms from Amiram Eldar, Mar 04 2020
STATUS
approved