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This sequence is also decimal expansion of cosine of 54 degrees. - Mohammad K. Azarian, Jun 29 2013
Zak Seidov, Table of n, a(n) for n = 0..999
Wikipedia, Exact trigonometric constants
sqrt((1/8)*(5 - sqrt(5))) = 0.5877852522924731291687059546390...
(PARI) sin(Pi/5) \\ Michel Marcus, Apr 25 2015
Cf. A019827 (sine of 18 degrees).
Sequence in context: A243598 A230366 A197415 * A143618 A177056 A053787
Adjacent sequences: A019842 A019843 A019844 * A019846 A019847 A019848
N. J. A. Sloane.