A343061 - OEIS

%I #18 Apr 27 2021 02:14:00

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

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

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

%N Decimal expansion of tan(Pi/17).

%C Root of the equation 17 - 680*x^2 + 6188*x^4 - 19448*x^6 + 24310*x^8 - 12376*x^10 + 2380*x^12 - 136*x^14 + x^16 = 0. - _Vaclav Kotesovec_, Apr 04 2021

%F Equals sqrt((-2*(-8 + sqrt(2*(15 + sqrt(17) - sqrt(34 - 2*sqrt(17)) + sqrt(2*(34 + 6*sqrt(17) - sqrt(578 - 34*sqrt(17)) + sqrt(34 - 2*sqrt(17)) + 8*sqrt(2*(17 + sqrt(17)))))))))/(15 + sqrt(17) + sqrt(34 - 2*sqrt(17)) + sqrt(2*(34 + 6*sqrt(17) + sqrt(578 - 34*sqrt(17)) - sqrt(34 - 2*sqrt(17)) - 8*sqrt(2*(17 + sqrt(17))))))). - _Vaclav Kotesovec_, Apr 04 2021

%e 0.18693239710797714594807628412307...

%t RealDigits[Tan[Pi/17], 10, 100][[1]] (* _Amiram Eldar_, Apr 27 2021 *)

%o (PARI) tan(Pi/17)

%Y Cf. A241243 (sin(Pi/17)), A210649 (cos(Pi/17)).

%K nonn,cons,easy

%O 0,2

%A _Seiichi Manyama_, Apr 04 2021