1,1

All the palindromic numbers with an even number of digits are divisible by 11. The number of palindromic numbers with 2*k+1 digits that are divisible by 11 is (10^(k+1) + (-1)^k)/11, and their asymptotic relative density within the set of all palindromic numbers with an odd number of digits (A056525) is 1/11 (Schmidt, 1988). - Amiram Eldar, Jan 11 2021

Amiram Eldar, Table of n, a(n) for n = 1..10000

Harvey Schmidt, Jr., Palindromes: Density and Divisibility, Mathematics Magazine, Vol. 61, No. 5 (1988), pp. 297-300.

Select[11 * Range[4000], PalindromeQ[#] && OddQ[IntegerLength[#]] &] (* Amiram Eldar, Jan 11 2021 *)

Intersection of A056525 and A083852.

Sequence in context: A084998 A082944 A131973 * A088285 A218172 A083749

Adjacent sequences: A045568 A045569 A045570 * A045572 A045573 A045574

base,nonn

approved