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 A019851 Decimal expansion of sine of 42 degrees. 5

%I

%S 6,6,9,1,3,0,6,0,6,3,5,8,8,5,8,2,1,3,8,2,6,2,7,3,3,3,0,6,8,6,7,8,0,4,

%T 7,3,5,9,9,5,8,3,2,1,8,9,5,9,7,9,5,6,7,6,8,1,7,4,5,3,3,5,2,2,8,7,9,6,

%U 6,6,0,1,7,1,0,6,4,3,8,9,7,1,4,6,1,5,4,9,2,3,3,6,0,0,9,0,0,6,7

%N Decimal expansion of sine of 42 degrees.

%C This sequence is also decimal expansion of cosine of 48 degrees. - _Mohammad K. Azarian_, Jun 29 2013

%C A quartic number with denominator 2. - _Charles R Greathouse IV_, Nov 05 2017

%H Ivan Panchenko, <a href="/A019851/b019851.txt">Table of n, a(n) for n = 0..1000</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Exact_trigonometric_constants">Exact trigonometric constants</a>

%F Equals cos (4*Pi/15) = [sqrt(5)-1]*[sqrt(3)*sqrt{5+2*sqrt(5)}-1]/8 = 8*A019887^4 -8*A019887^2+1 = sqrt(1-A019857^2) - _R. J. Mathar_, Jun 18 2006

%o (PARI) sin(7/30*Pi) \\ _Charles R Greathouse IV_, Nov 05 2017

%K nonn,cons

%O 0,1

%A _N. J. A. Sloane_.

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Last modified February 19 09:33 EST 2020. Contains 332041 sequences. (Running on oeis4.)