id:A140277 - OEIS Search Results

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Rounded (first-quadrant) angle in degrees whose tangent is n.

+0
3

0, 45, 63, 72, 76, 79, 81, 82, 83, 84, 84, 85, 85, 86, 86, 86, 86, 87, 87, 87, 87, 87, 87, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 88, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89 (list; graph; listen)

	OFFSET	`0,2`
	COMMENT	`180*atan(n)/Pi is an exact integer only for n = 0 and n = 1 (and n = -1). a(n) = 90 for n >= 115.`
	FORMULA	`For all integers n, a(n) = round(180*atan(n)/Pi) = -a(-n), where a negative term represents a fourth-quadrant angle. Terms shown are only for n >= 0.`
	EXAMPLE	`a(1) = 45 degrees as that is the first-quadrant angle with tan(45 deg) = 1. a(3) = 72 degrees as 180*atan(3)/Pi = 71.5650... and 71.5650... rounded to the nearest integer is 72. (Method is .5000... rounds up.)`
	PROGRAM	`(PARI) a(n) = round(180*atan(n)/Pi)`
	CROSSREFS	`Cf. A140276, A140278.` `Sequence in context: A151743 A138046 A140276 this_sequence A077646 A046364 A051773` `Adjacent sequences: A140274 A140275 A140276 this_sequence A140278 A140279 A140280`
	KEYWORD	`nonn`
	AUTHOR	`Rick L. Shepherd (rshepherd2(AT)hotmail.com), May 16 2008`

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Last modified December 1 19:22 EST 2009. Contains 167811 sequences.

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