“…c 3 c 2 c 1 (thus it can be said that they are "symmetrical" with respect to an axis of symmetry). The first 19th palindromic numbers are 0, 1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99 and clearly they are a repdigits type. A number n is called repdigit if it has only one repeated digit in its decimal expansion.…”