This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A019819 #50 Aug 31 2025 11:29:05 %S A019819 1,7,3,6,4,8,1,7,7,6,6,6,9,3,0,3,4,8,8,5,1,7,1,6,6,2,6,7,6,9,3,1,4,7, %T A019819 9,6,0,0,0,3,7,5,6,7,7,1,8,4,0,6,9,3,8,7,2,3,6,2,4,1,3,7,8,1,3,2,0,6, %U A019819 5,8,2,2,1,3,9,0,1,4,7,3,5,4,2,1,5,1,6,6,1,3,1,5,7,3,9,9,5,7,4 %N A019819 Decimal expansion of sine of 10 degrees. %C A019819 Also the imaginary part of i^(1/9). - _Stanislav Sykora_, Apr 25 2012 %H A019819 Ivan Panchenko, <a href="/A019819/b019819.txt">Table of n, a(n) for n = 0..1000</a> %H A019819 Vladimir Ivanovich Smirnov, <a href="https://archive.org/details/v-i-smirnov.-a-course-of-higher-mathematics-vol-1/page/342/mode/2up">A course of higher mathematics</a>, vol. 1 , Pergamon Press, 1964, p. 342. %H A019819 <a href="/index/Al#algebraic_03">Index entries for algebraic numbers, degree 3</a>. %F A019819 Equals cos(4*Pi/9) = 2F1(7/6,-1/6;1/2;3/4) / 2 = - 2F1(4/3,-1/3;1/2;3/4) / 2. - _R. J. Mathar_, Oct 27 2008 %F A019819 From _Artur Jasinski_, Oct 28 2008: (Start) %F A019819 Decimal expansion of root of cubic polynomial 1 - 6*x + 8*x^3. (Others A019859, -A019879) %F A019819 Decimal expansion of casus irreducibilis: %F A019819 (1/2) * (((-i*sqrt(3) - 1)/2)^(2/3) + ((i*sqrt(3) - 1)/2)^(2/3)). (End) %F A019819 Equals 2 * A019814 * A019894. - _R. J. Mathar_, Jan 17 2021 %F A019819 This^2 + A019889^2 = 1. - _R. J. Mathar_, Aug 31 2025 %e A019819 0.173648177... %t A019819 First[RealDigits[Root[1 - 6 #1 + 8 #1^3 &, 2], 10, 100]] (* _Artur Jasinski_, Oct 28 2008 *) %t A019819 RealDigits[ Sin[Pi/18], 10, 111] (* _Robert G. Wilson v_ *) %o A019819 (PARI) sin(Pi/18) \\ _Charles R Greathouse IV_, Apr 25 2012 %Y A019819 Cf. A019814. %K A019819 nonn,cons,changed %O A019819 0,2 %A A019819 _N. J. A. Sloane_