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A019875
Decimal expansion of sine of 66 degrees.
10
9, 1, 3, 5, 4, 5, 4, 5, 7, 6, 4, 2, 6, 0, 0, 8, 9, 5, 5, 0, 2, 1, 2, 7, 5, 7, 1, 9, 8, 5, 3, 1, 7, 1, 7, 7, 9, 4, 0, 8, 1, 0, 4, 5, 9, 3, 7, 7, 4, 7, 4, 5, 4, 5, 0, 6, 0, 9, 9, 9, 7, 8, 8, 0, 6, 5, 1, 1, 4, 8, 8, 2, 1, 0, 2, 6, 3, 1, 2, 7, 1, 6, 8, 1, 7, 8, 4, 0, 0, 0, 8, 9, 3, 2, 9, 9, 9, 9, 4
OFFSET
0,1
COMMENTS
A quartic number with denominator 2. - Charles R Greathouse IV, Aug 27 2017
FORMULA
Equals cos(2*Pi/15) = 2*A019887^2 - 1 = 1 - 2*A019821^2. - R. J. Mathar, Jun 18 2006
Equals 2*A019842*A019866. - R. J. Mathar, Jan 17 2021
EXAMPLE
0.913545457...
MATHEMATICA
RealDigits[N[Cos[2*Pi/15], 110]][[1]] (* Wesley Ivan Hurt, Dec 27 2021 *)
PROG
(PARI) cos(2*Pi/15) \\ Charles R Greathouse IV, Aug 27 2017
CROSSREFS
KEYWORD
nonn,cons
STATUS
approved