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A062917
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Nonpalindromic numbers k such that k is not divisible by 10 and k*R(k) is a square, where R(k) is the reversal of k (A004086).
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7
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144, 169, 288, 441, 528, 768, 825, 867, 882, 961, 1089, 1584, 2178, 4851, 8712, 9801, 10404, 10609, 10989, 12544, 12769, 13104, 14544, 14884, 15984, 20808, 21978, 26208, 27648, 27848, 36828, 40131, 40401, 44521, 44541, 48139, 48841, 48951
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OFFSET
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1,1
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COMMENTS
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The sequence has infinitely many terms, some of which can be derived from 1089 and 2178.
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LINKS
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Giovanni Resta, Table of n, a(n) for n = 1..2338 (terms < 10^12, n = 1..150 from Harvey P. Dale, n = 151..1000 from Chai Wah Wu)
Eric Weisstein's World of Mathematics, Reversal
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EXAMPLE
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2178 is a term as 2178*8712 = 4356^2.
10891089 is a term as 10891089*98019801 = 32673267^2.
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MATHEMATICA
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okQ[n_]:=Module[{idn=IntegerDigits[n], ridn}, ridn=Reverse[idn]; idn!= ridn && !Divisible[n, 10]&&IntegerQ[Sqrt[n FromDigits[ridn]]]]; Select[Range[ 50000], okQ] (* Harvey P. Dale, Dec 08 2012 *)
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CROSSREFS
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Cf. A004086.
Subsequence of A029742.
Sequence in context: A205190 A085426 A034289 * A035090 A064021 A156316
Adjacent sequences: A062914 A062915 A062916 * A062918 A062919 A062920
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KEYWORD
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nonn,base,easy
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AUTHOR
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Amarnath Murthy, Jul 02 2001
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EXTENSIONS
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More terms from Reiner Martin (reinermartin(AT)hotmail.com), Jul 10 2001
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STATUS
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approved
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