Several types of numerical palindromes have appeared in Word Ways (Susan Thorpe, Numerical Palindromes: Part 1 in Nov 1996 and Rex Gooch, Numerical Palindromes: Part 2 in Feb 1997). However, I believe the current exercise is the first to make two or more numerically-palindromic 'offspring' from the letters of a numerically-palindromic 'parent'. In other words, numerical palindromes beget numerical palindromes.
"Numerical Palindromes: The Next Generation,"
Word Ways: Vol. 37
, Article 19.
Available at: http://digitalcommons.butler.edu/wordways/vol37/iss3/19