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A016113
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Numbers whose square is a palindrome with an even number of digits.
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4
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836, 798644, 64030648, 83163115486, 6360832925898, 69800670077028, 98275825201587, 6819209882215742, 40447213778058769, 404099764753665981, 633856150760638652, 795559265009384106, 637323988797048057098, 3823177109095314778621
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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Further terms, listed on P. De Geest's page, are 722956456358957313434535, 831775153121251039203514, 4275548277509699161443659 and 64897400105515621177314682. - M. F. Hasler, Jun 08 2014
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REFERENCES
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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]
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LINKS
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PROG
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(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
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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Two new terms were recently found by Bennett from UK (communication from Patrick De Geest)
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STATUS
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approved
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