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Palindromic hypotenuses in primitive Pythagorean triples.
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%I #11 Sep 06 2018 19:23:15

%S 5,101,181,313,353,373,505,545,565,757,797,929,949,10001,10201,10301,

%T 10501,10601,12421,12721,12821,14341,14741,16061,16361,16561,16661,

%U 16861,18181,18281,18481,18581,31013,31313,31513,31613,31813,33133

%N Palindromic hypotenuses in primitive Pythagorean triples.

%C For prime terms in this sequence, see A081220. - _Lekraj Beedassy_, Jun 30 2008

%t Take[Select[Sqrt[#[[1]]^2+#[[2]]^2]&/@(Union[Sort/@({Times@@#,(Last[#]^2- First[#]^2)/2}&/@(Select[Subsets[Range[1,311,2],{2}],GCD@@#== 1&]))]), PalindromeQ]//Union,50] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Sep 06 2018 *)

%Y Cf. A020882.

%K nonn,base

%O 1,1

%A _Lekraj Beedassy_, Oct 23 2003

%E More terms from _Ray Chandler_, Oct 25 2003