id:A049008 - OEIS Search Results

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Greatest possible number of right angles that can occur as interior angles in a planar n-gon.

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1, 4, 3, 5, 5, 6, 7, 7, 8, 9, 9, 10, 11, 11, 12, 13, 13, 14, 15, 15, 16, 17, 17, 18, 19, 19, 20, 21, 21, 22, 23, 23, 24, 25, 25, 26, 27, 27, 28, 29, 29, 30, 31, 31, 32, 33, 33, 34, 35, 35, 36, 37, 37, 38, 39, 39, 40, 41, 41, 42, 43, 43, 44, 45, 45, 46, 47, 47, 48, 49, 49, 50 (list; graph; listen)

	OFFSET	`3,2`
	COMMENT	`Reflex angles (e.g. 270 degrees) are not considered right angles. From a(6) on, this duplicates A004396 from its eighth term.`
	FORMULA	`a(3) = 1; a(4) = 4; a(5) = 3; a(3k+3) = 2k+3; a(3k+4) = 2k+3; a(3k+5) = 2k+4 where k starts from 1 OR a(n) is the greatest integer less than 2/3*(n+2) where n starts from 6.`
	EXAMPLE	`a(3) = 1 because you can only have one right angle in a triangle; a(4) = 4 as in a rectangular quadrilateral; a(100) = 67 etc.`
	CROSSREFS	`Cf. A004396.` `Sequence in context: A134186 A024688 A024477 this_sequence A133981 A016701 A023829` `Adjacent sequences: A049005 A049006 A049007 this_sequence A049009 A049010 A049011`
	KEYWORD	`easy,nonn`
	AUTHOR	`Deepak R. N (deepak_rama(AT)bigfoot.com)`

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Last modified July 19 08:04 EDT 2008. Contains 142098 sequences.

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