This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A263611 #14 Aug 16 2022 16:08:36
%S A263611 0,1,2,11,101,111,231,1001,1111,10001,10101,11011,11204,100001,101101,
%T A263611 110011,242204,1000001,1001001,1010101,1042214,1100011,2020303,
%U A263611 2043122,2443304,10000001,10011001,10100101,11000011,100000001,100010001,100101001,101000101,110000011,111103411
%N A263611 Base 5 numbers whose square is a palindrome in base 5.
%C A263611 A029988 expressed in base 5.
%H A263611 G. J. Simmons, <a href="/A002778/a002778.pdf">On palindromic squares of non-palindromic numbers</a>, J. Rec. Math., 5 (No. 1, 1972), 11-19. [Annotated scanned copy]
%F A263611 a(n) = A007091(A029988(n)).
%t A263611 With[{b = 5}, FromDigits@ IntegerDigits[#, b] & /@ Select[Range[b^9], PalindromeQ[IntegerDigits[#^2, b]] &]] (* _Michael De Vlieger_, Aug 15 2022 *)
%Y A263611 Cf. A007091, A002778, A029988, A263612, A029989.
%K A263611 nonn,base
%O A263611 1,3
%A A263611 _N. J. A. Sloane_, Oct 23 2015
%E A263611 Name corrected by _Charles R Greathouse IV_, Aug 15 2022