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 A144981 Decimal expansion of cos(Pi/8) = cos(22.5 degrees). 8
 9, 2, 3, 8, 7, 9, 5, 3, 2, 5, 1, 1, 2, 8, 6, 7, 5, 6, 1, 2, 8, 1, 8, 3, 1, 8, 9, 3, 9, 6, 7, 8, 8, 2, 8, 6, 8, 2, 2, 4, 1, 6, 6, 2, 5, 8, 6, 3, 6, 4, 2, 4, 8, 6, 1, 1, 5, 0, 9, 7, 7, 3, 1, 2, 8, 0, 5, 3, 5, 0, 0, 7, 5, 0, 1, 1, 0, 2, 3, 5, 8, 7, 1, 4, 8, 3, 9, 9, 3, 4, 8, 5, 0, 3, 4, 4, 5, 9, 6, 0, 9, 7, 9, 6, 3 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Also the real part of i^(1/4). - Stanislav Sykora, Apr 25 2012 LINKS Wikipedia, Exact trigonometric constants. FORMULA (2+2^(1/2))^(1/2)/2 = sqrt(3.41421....)/2 = 1.8477759.../2 . Equals 2F1(11/16,5/16;1/2;3/4) / 2. - R. J. Mathar, Oct 27 2008 EXAMPLE Equals 0.923879532511286756128183189396788286822416625863642486115097... MAPLE evalf(sqrt(2+sqrt(2))/2) ; MATHEMATICA RealDigits[ Sqrt[2 + Sqrt[2]]/2, 10, 111][[1]] (* Or *) RealDigits[ Cos[Pi/8], 10, 111][[1]] (* Robert G. Wilson v *) PROG (PARI) cos(Pi/8) \\ Michel Marcus, Dec 15 2015 CROSSREFS Cf. A019863: cos(Pi/5); A010527: cos(Pi/6); A073052: cos(Pi/7); A019879: cos(Pi/9). Sequence in context: A011344 A257959 A137197 * A215267 A248322 A248321 Adjacent sequences:  A144978 A144979 A144980 * A144982 A144983 A144984 KEYWORD cons,easy,nonn AUTHOR R. J. Mathar, Sep 28 2008 STATUS approved

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