id:A070109 - OEIS Search Results

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Number of right integer triangles with perimeter n and relatively prime side lengths.

+0
11

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; listen)

	OFFSET	`1,1`
	COMMENT	`a(n)<=A024155(n); a(n)=A051493(n)-A070094(n)-A070102(n);` `right integer triangles have integer areas: see A070142, A051516.` `a(n) is nonzero iff n is in A024364.`
	LINKS	`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.`
	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: A011727 A088918 A011726 this_sequence A107846 A065202 A045701` `Adjacent sequences: A070106 A070107 A070108 this_sequence A070110 A070111 A070112`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 05 2002`

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Last modified November 24 23:16 EST 2009. Contains 167481 sequences.

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