Overview What does “rare” really mean? In calculus, a number is called rare if it:is a non-palindromic integer and,has the property that n+r and n−r are both square, where r is the reversal of n (65 is the reversal of 56).so much term, right? But don’t worry, it’s straight forward definition once the terms are clear. Simply put, a palindromic number is a palindrome (a sequence of objects that stays the same when reversed), e.g., 77, 99, and 101. Thus, the sequence of rare numbers begins with ...

Overview What does “rare” really mean? In calculus, a number is called rare if it:is a non-palindromic integer and,has the property that n+r and n−r are both square, where r is the reversal of n (65 is the reversal of 56).so much term, right? But don’t worry, it’s straight forward definition once the terms are clear. Simply put, a palindromic number is a palindrome (a sequence of objects that stays the same when reversed), e.g., 77, 99, and 101. Thus, the sequence of rare numbers begins with ...