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A019818
Decimal expansion of sine of 9 degrees.
8
1, 5, 6, 4, 3, 4, 4, 6, 5, 0, 4, 0, 2, 3, 0, 8, 6, 9, 0, 1, 0, 1, 0, 5, 3, 1, 9, 4, 6, 7, 1, 6, 6, 8, 9, 2, 3, 1, 3, 8, 9, 9, 8, 9, 2, 0, 8, 5, 6, 6, 0, 7, 9, 0, 0, 8, 4, 6, 4, 1, 3, 4, 6, 0, 5, 7, 7, 5, 8, 7, 9, 3, 3, 0, 5, 6, 2, 3, 5, 7, 9, 3, 3, 6, 6, 9, 5, 8, 7, 2, 6, 7, 6, 8, 4, 8, 6, 8, 8
OFFSET
0,2
COMMENTS
Also the imaginary part of i^(1/10). - Stanislav Sykora, Apr 25 2012
An algebraic number of degree 8 and denominator 2. - Charles R Greathouse IV, Aug 27 2017
FORMULA
sqrt(8-2*sqrt(10+2*sqrt(5)))/4 = sqrt((1/2)*(1 - sqrt((1/8)*(5 + sqrt(5))))). - Herman Jamke (hermanjamke(AT)fastmail.fm), Nov 13 2006
Equals A019815*A019896 + A019812*A019893. - R. J. Mathar, Jan 27 2021
EXAMPLE
0.1564344650402308690101053194671668923138...
MATHEMATICA
RealDigits[Sin[9 Degree], 10, 120][[1]] (* Harvey P. Dale, Sep 15 2014 *)
PROG
(PARI) sin(Pi/20) \\ Charles R Greathouse IV, Aug 27 2017
CROSSREFS
KEYWORD
nonn,cons
STATUS
approved