Search: id:A070109
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%I A070109
%S A070109 0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,
%T A070109 0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,1,
%U A070109 0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
%N A070109 Number of right integer triangles with perimeter n and relatively prime 
               side lengths.
%C A070109 a(n)<=A024155(n); a(n)=A051493(n)-A070094(n)-A070102(n);
%C A070109 right integer triangles have integer areas: see A070142, A051516.
%C A070109 a(n) is nonzero iff n is in A024364.
%H A070109 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               RightTriangle.html">Right Triangle</a>.
%H A070109 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               PythagoreanTriple.html">Pythagorean Triples</a>.
%H A070109 R. Zumkeller, <a href="a070080.txt">Integer-sided triangles</a>
%F A070109 a(n)=A078926(n/2) if n is even; a(n)=0 if n is odd.
%e A070109 For n=30 there are A005044(30) = 19 integer triangles; only one is right: 
               5+12+13=30, 5^2+12^2 = 13^2; therefore a(30) = 1.
%Y A070109 Cf. A070080, A070081, A070082, A051493, A070093, A070101, A070138, A070084, 
               A070137.
%Y A070109 Sequence in context: A011727 A088918 A011726 this_sequence A107846 A065202 
               A045701
%Y A070109 Adjacent sequences: A070106 A070107 A070108 this_sequence A070110 A070111 
               A070112
%K A070109 nonn
%O A070109 1,1
%A A070109 Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 05 2002

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