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A078927
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Smallest s for which there are exactly n primitive Pythagorean triangles with perimeter 2s; i.e., smallest s such that A078926(s) = n.
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3
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6, 858, 7140, 158730, 771342, 3120180, 9699690, 31651620, 119584290, 198843645, 229474245, 406816410, 281291010, 1412220810, 1673196525, 3457939485, 3234846615, 4360010655, 4573403835, 4127218095, 11532931410, 12929686770, 101268227775
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OFFSET
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1,1
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COMMENTS
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A Pythagorean triangle is a right triangle whose edge lengths are all integers; such a triangle is 'primitive' if the lengths are relatively prime.
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LINKS
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EXAMPLE
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a(2)=858; the primitive Pythagorean triangles with edge lengths (364, 627, 725) and (195, 748, 773) both have perimeter 2*858 = 1716.
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MATHEMATICA
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oddpart[n_] := If[OddQ[n], n, oddpart[n/2]]; ct[p_] := Length[Select[Divisors[oddpart[p/2]], p/2<#^2<p&&GCD[ #, p/2/# ]==1&]]; a[n_] := For[s=1, True, s++, If[ct[2s]==n, Return[s]]]
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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