Palindromes in Different Bases: A Conjecture of J. Ernest Wilkins

Abstract

We show that there exist exactly 203 positive integers $N$ such that for some integer $d \geq 2$ this number is a $d$-digit palindrome base 10 as well as a $d$-digit palindrome for some base $b$ different from 10. To be more precise, such $N$ range from 22 to 9986831781362631871386899