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a(n) is the number of unit perimeter triangles with rational side lengths whose largest denominator is less than or equal to n.
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%I #12 Nov 09 2020 21:35:57

%S 0,0,1,1,2,2,4,5,7,8,12,14,19,21,26,30,38,42,52,60,70,76,90,98,113,

%T 122,138,152,173,186,210,226,249,265,306,324,357,377,410,442,482,514,

%U 558,592,645,675,727,759,813,848,902,950,1015,1053,1140,1210,1277,1326

%N a(n) is the number of unit perimeter triangles with rational side lengths whose largest denominator is less than or equal to n.

%C Partial sums of A338201.

%C a(n) is bounded above by A180360(n,3).

%H Peter Kagey, <a href="/A338202/b338202.txt">Table of n, a(n) for n = 1..300</a>

%e For n = 8, the a(8) = 5 triangles have side lengths

%e 1/3, 1/3, 1/3;

%e 1/5, 2/5, 2/5;

%e 2/7, 2/7, 3/7;

%e 1/7, 3/7, 3/7; and

%e 1/4, 3/8, 3/8.

%Y Cf. A180360, A338201.

%K nonn

%O 1,5

%A _Peter Kagey_, Oct 16 2020