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Decimal expansion of Ls_4(Pi/3), the value of the 4th basic generalized log-sine integral at Pi/3.
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%I #8 Apr 06 2024 13:42:12

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

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

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

%N Decimal expansion of Ls_4(Pi/3), the value of the 4th basic generalized log-sine integral at Pi/3.

%H Jonathan M. Borwein, Armin Straub, <a href="https://carmamaths.org/resources/jon/logsin3.pdf">Special Values of Generalized Log-sine Integrals</a>.

%F -Integral_{0..Pi/3} log(2*sin(x/2))^3 dx = (1/2)*Pi*zeta(3) + (9/4)*im( PolyLog(4, (-1)^(1/3)) - PolyLog(4, -(-1)^(2/3))).

%F Also equals 6 * 5F4(1/2,1/2,1/2,1/2,1/2; 3/2,3/2,3/2,3/2; 1/4) (with 5F4 the hypergeometric function).

%e 6.00949754981888891620478870620327074059696329743956841883606392675151...

%t RealDigits[(1/2)*Pi*Zeta[3] + (9/4)*Im[ PolyLog[4, (-1)^(1/3)] - PolyLog[4, -(-1)^(2/3)]], 10, 105] // First

%Y Cf. A258749 (Ls_3(Pi)), A258750 (Ls_4(Pi)), A258751 (Ls_5(Pi)), A258752 (Ls_6(Pi)), A258753 (Ls_7(Pi)), A258754 (Ls_8(Pi)).

%Y Cf. A143298 (Ls_2(Pi/3)), A258759 (Ls_3(Pi/3)), A258761 (Ls_5(Pi/3)), A258762 (Ls_6(Pi/3)), A258763 (Ls_7(Pi/3)).

%K nonn,cons,easy

%O 1,1

%A _Jean-François Alcover_, Jun 09 2015