A028816 Numbers k such that k^2 is a palindrome with an odd number of digits.

0, 1, 2, 3, 11, 22, 26, 101, 111, 121, 202, 212, 264, 307, 1001, 1111, 2002, 2285, 2636, 10001, 10101, 10201, 11011, 11111, 11211, 20002, 20102, 22865, 24846, 30693, 100001, 101101, 110011, 111111, 200002, 1000001, 1001001, 1002001, 1010101, 1011101, 1012101

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• base

Links

• P. De Geest, Subsets of Palindromic Squares

Crossrefs

Cf. A028817.

Programs

Mathematica

id[n_]:=IntegerDigits[n]; palQ[n_]:=FromDigits[Reverse[id[n]]]==n; t={}; Do[If[palQ[x=n^2] && OddQ[Length[id[x]]], AppendTo[t,n]],{n,1012102}]; t (* Jayanta Basu, May 13 2013 *)
Join[{0},Select[Range[11 10^5],OddQ[IntegerLength[#^2]]&&PalindromeQ[#^2]&]] (* Harvey P. Dale, Jul 18 2025 *)