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 A019968 #22 Aug 29 2025 12:37:31 %S A019968 2,7,4,7,4,7,7,4,1,9,4,5,4,6,2,2,2,7,8,7,6,1,6,6,4,0,2,6,4,9,7,6,7,2, %T A019968 7,1,7,7,5,1,8,7,2,5,9,9,1,7,0,8,2,5,8,2,1,5,0,5,2,7,3,0,0,2,5,1,9,8, %U A019968 9,8,2,5,3,8,8,1,5,9,3,1,8,4,3,4,0,6,0,4,2,4,5,9,5,0,7,0,1,8,5 %N A019968 Decimal expansion of tangent of 70 degrees. %C A019968 Also the decimal expansion of cotangent of 20 degrees. - _Ivan Panchenko_, Sep 01 2014 %C A019968 An algebraic number of degree 6 and denominator 3. - _Charles R Greathouse IV_, Aug 27 2017 %H A019968 Ivan Panchenko, <a href="/A019968/b019968.txt">Table of n, a(n) for n = 1..1000</a> %H A019968 <a href="/index/Al#algebraic_06">Index entries for algebraic numbers, degree 6</a> %F A019968 Equals A019879/A019829. - _R. J. Mathar_, Aug 29 2025 %F A019968 Largest positive of the 6 real-values roots of 3*x^6 -27*x^4 +33*x^2 -1 =0. (Others: A019948, A019908). - _R. J. Mathar_, Aug 29 2025 %e A019968 2.7474774194546222787616640264976727177518725991708258215... %t A019968 RealDigits[Tan[7*Pi/18], 10, 100][[1]] (* _G. C. Greubel_, Nov 21 2018 *) %o A019968 (PARI) tan(7*Pi/18) \\ _Charles R Greathouse IV_, Aug 27 2017 %o A019968 (Magma) SetDefaultRealField(RealField(100)); R:= RealField(); Tan(7*Pi(R)/18); // _G. C. Greubel_, Nov 21 2018 %o A019968 (Sage) numerical_approx(tan(7*pi/18), digits=100) # _G. C. Greubel_, Nov 21 2018 %Y A019968 Cf. A019879 (sine of 70 degrees). %K A019968 nonn,cons,changed %O A019968 1,1 %A A019968 _N. J. A. Sloane_