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%I #29 Feb 10 2025 23:55:58
%S 0,1,2,4,10,11,20,22,28,34,56,82,89,113,154,164,244,262,488,524,730,
%T 755,802,862,1021,1342,1358,1460,2188,2242,2684,2716,3046,4276,4376,
%U 4484,6562,6641,6778,8030,8215,8350,8887,12482,13124,14810,19684
%N Numbers k such that k^2 is palindromic in base 3.
%H Giovanni Resta, <a href="/A029984/b029984.txt">Table of n, a(n) for n = 1..400</a> (first 100 terms from Harvey P. Dale)
%H Patrick De Geest, <a href="https://www.worldofnumbers.com/nobase10pg2.htm">Palindromic Squares in bases 2 to 17</a>
%H 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]
%t pal3Q[n_]:=Module[{idn3=IntegerDigits[n^2,3]},idn3==Reverse[idn3]]; Select[Range[0,20000],pal3Q] (* _Harvey P. Dale_, May 22 2012 *)
%Y Cf. A002778, A003166, A007089, A029985, A263607, A263608.
%K nonn,base,changed
%O 1,3
%A _Patrick De Geest_