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%I #25 Oct 11 2019 18:58:19
%S 836,798644,64030648,83163115486,6360832925898,69800670077028,
%T 98275825201587,6819209882215742,40447213778058769,404099764753665981,
%U 633856150760638652,795559265009384106,637323988797048057098,3823177109095314778621
%N Numbers whose square is a palindrome with an even number of digits.
%C Further terms, listed on P. De Geest's page, are 722956456358957313434535, 831775153121251039203514, 4275548277509699161443659 and 64897400105515621177314682. - _M. F. Hasler_, Jun 08 2014
%C For the squares, see A027829(n) = a(n)^2. - _M. F. Hasler_, Oct 11 2019
%D C. Ashbacher, More on palindromic squares, J. Rec. Math. 22, no. 2 (1990), 133-135. [A scan of the first page of this article is included with the last page of the Keith (1990) scan]
%H K. S. Brown, <a href="http://www.mathpages.com/home/kmath359.htm">On General Palindromic Numbers</a>
%H P. De Geest, <a href="http://www.worldofnumbers.com/square.htm">Palindromic Squares</a>
%H P. De Geest, <a href="http://www.worldofnumbers.com/subsquar.htm">Subsets of Palindromic Squares</a>
%H M. Keith, <a href="/A002778/a002778_1.pdf">Classification and enumeration of palindromic squares</a>, J. Rec. Math., 22 (No. 2, 1990), 124-132. [Annotated scanned copy]
%H F. Yuan, <a href="http://www.fengyuan.com/palindrome.html">Palindromic Square Numbers</a>, as of July 2002.
%o (PARI) is_A016113(n)={Vecrev(n=digits(n^2))==n&&!bittest(#n,0)} \\ This is faster than first checking for even length, if applied to numbers in a range where the squares are known to have an even number of digits, as should be the case for a systematic search. - _M. F. Hasler_, Jun 08 2014
%Y Cf. A027829. A proper subset of A002778.
%K nonn,base
%O 1,1
%A _Robert G. Wilson v_
%E Two new terms were recently found by Bennett from UK (communication from _Patrick De Geest_)
%E Edited by _M. F. Hasler_, Jun 08 2014
%E Missing a(10) inserted by _M. F. Hasler_, Oct 11 2019
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