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A070203
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Number of scalene integer triangles with perimeter n having integral inradius.
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4
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 1, 0, 2, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 3, 0, 0, 0, 1, 0, 1, 0, 1, 0, 2, 0, 2, 0, 0, 0, 1, 0, 1, 0, 2, 0, 0, 0, 8, 0, 0, 0, 1, 0, 3
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OFFSET
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1,36
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COMMENTS
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LINKS
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Eric Weisstein's World of Mathematics, Incircle.
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PROG
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(Ruby)
def A(n)
cnt = 0
(1..n / 3).each{|a|
(a + 1..(n - a) / 2).each{|b|
c = n - a - b
if a + b > c && b < c
s = n / 2r
t = (s - a) * (s - b) * (s - c) / s
if t.denominator == 1
t = t.to_i
cnt += 1 if Math.sqrt(t).to_i ** 2 == t
end
end
}
}
cnt
end
(1..n).map{|i| A(i)}
end
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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