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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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%I #23 Oct 30 2022 18:19:59

%S 144,169,288,441,528,768,825,867,882,961,1089,1584,2178,4851,8712,

%T 9801,10404,10609,10989,12544,12769,13104,14544,14884,15984,20808,

%U 21978,26208,27648,27848,36828,40131,40401,44521,44541,48139,48841,48951

%N 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).

%C The sequence has infinitely many terms, some of which can be derived from 1089 and 2178.

%H Giovanni Resta, <a href="/A062917/b062917.txt">Table of n, a(n) for n = 1..2338</a> (terms < 10^12, n = 1..150 from Harvey P. Dale, n = 151..1000 from Chai Wah Wu)

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Reversal.html">Reversal</a>

%e 2178 is a term as 2178*8712 = 4356^2.

%e 10891089 is a term as 10891089*98019801 = 32673267^2.

%t 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 *)

%Y Cf. A004086.

%Y Subsequence of A029742.

%K nonn,base,easy

%O 1,1

%A _Amarnath Murthy_, Jul 02 2001

%E More terms from _Reiner Martin_, Jul 10 2001