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A140277
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Rounded (first-quadrant) angle in degrees whose tangent is n.
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2
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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; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| 180*atan(n)/Pi is an exact integer only for n = 0 and n = 1 (and n = -1). a(n) = 90 for n >= 115.
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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.
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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.)
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PROG
| (PARI) a(n) = round(180*atan(n)/Pi)
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CROSSREFS
| Cf. A140276, A140278.
Sequence in context: A179007 A138046 A140276 * A077646 A175761 A046364
Adjacent sequences: A140274 A140275 A140276 * A140278 A140279 A140280
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KEYWORD
| nonn
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AUTHOR
| Rick L. Shepherd (rshepherd2(AT)hotmail.com), May 16 2008
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