palindrome | palindrome number

A palindromic number is a number (in some base b) that is the same when written forwards or backwards, i.e., of the form a_1 a_2 ...a_2 a_1. The first few palindromic numbers are therefore are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 66, 77, 88, 99, 101, 111, 121, ... (OEIS A002113). The number of palindromic numbers less than a given number are illustrated in the plot above. A number n can be tested to see if it is palindromic in the Wolfram Language using PalindromeQ[n]. The numbers of palindromic numbers less than 10, 10^2, 10^3, ... are 9, 18, 108, 198, 1098, 1998, 10998, ... (OEIS A050250).

Belphegor number | Demlo number | palindromic number conjecture | palindromic prime | reversal | tetradic number