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 A070109 Number of right integer triangles with perimeter n and relatively prime side lengths. 13
 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, 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, 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1716 COMMENTS Right integer triangles have integer areas: see A070142, A051516. a(n) is nonzero iff n is in A024364. LINKS Antti Karttunen, Table of n, a(n) for n = 1..20000 (obtained from the b-file of A078926) Eric Weisstein's World of Mathematics, Right Triangle. Eric Weisstein's World of Mathematics, Pythagorean Triples. R. Zumkeller, Integer-sided triangles FORMULA a(n) = A078926(n/2) if n is even; a(n)=0 if n is odd. a(n) = A051493(n) - A070094(n) - A070102(n). a(n) <= A024155(n). EXAMPLE 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. CROSSREFS Cf. A070080, A070081, A070082, A051493, A070093, A070101, A070138, A070084, A070137. Sequence in context: A277163 A011726 A297041 * A107846 A179801 A065202 Adjacent sequences:  A070106 A070107 A070108 * A070110 A070111 A070112 KEYWORD nonn AUTHOR Reinhard Zumkeller, May 05 2002 EXTENSIONS Secondary offset added by Antti Karttunen, Oct 07 2017 STATUS approved

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Last modified May 8 20:32 EDT 2021. Contains 343668 sequences. (Running on oeis4.)