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 A070203 Number of scalene integer triangles with perimeter n having integral inradius. 4
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,36 COMMENTS a(n) = A070201(n) - A070204(n). LINKS Seiichi Manyama, Table of n, a(n) for n = 1..5000 Mohammad K. Azarian, Solution to Problem S125: Circumradius and Inradius, Math Horizons, Vol. 16, Issue 2, November 2008, p. 32. Eric Weisstein's World of Mathematics, Incircle. Eric Weisstein's World of Mathematics, Scalene Triangle. R. Zumkeller, Integer-sided triangles PROG (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 def A070203(n)   (1..n).map{|i| A(i)} end p A070203(100) # Seiichi Manyama, Oct 07 2017 CROSSREFS Cf. A024153, A005044. Sequence in context: A333146 A135767 A208575 * A070201 A070138 A024153 Adjacent sequences:  A070200 A070201 A070202 * A070204 A070205 A070206 KEYWORD nonn AUTHOR Reinhard Zumkeller, May 05 2002 STATUS approved

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Last modified June 1 13:11 EDT 2020. Contains 334762 sequences. (Running on oeis4.)