%I
%S 65,5625,6565,50721,65065,71555,75515,84295,541063,557931,650065,
%T 650606,656565,699796,809325,827372,934065,2855182,4637061,4854634,
%U 5791775,5883141,5951693,6129084,6500065,6731076,6752626,6791774,7768827,8084505,9349065
%N Nonpalindromic numbers m such that the difference between the square of m and the square of the reversal of m is itself a perfect square. Numbers ending in 0 are excluded.
%C This sequence is infinite because 65*10^k + 65 is a term for all k > 1.
%D A. H. Beiler, Recreations in the Theory of Numbers, Dover, NY, 1996, p. 147.
%H Giovanni Resta, <a href="/A202386/b202386.txt">Table of n, a(n) for n = 1..200</a>
%e 5625 belongs to this sequence because 5625^2  5265^2 = 1980^2.
%t lst = {}; Do[a = n^2; b = FromDigits[Reverse[IntegerDigits[n]]]^2; If[MatchQ[Sqrt[a  b], _Integer] && ! a == b, AppendTo[lst, n]], {n, 85000}]; Select[lst, ! Mod[#, 10] == 0 &]
%o (PARI) isok(m) = my(r=fromdigits(Vecrev(digits(m)))); (r != m) && (m % 10) && issquare(m^2  r^2); \\ _Michel Marcus_, Feb 27 2020
%Y Cf. A068536, A000290.
%K nonn,base
%O 1,1
%A _Arkadiusz Wesolowski_, Dec 18 2011
%E Name clarified by _Michel Marcus_, Feb 27 2020
