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 A257817 Decimal expansion of the real part of li(i), i being the imaginary unit. 4
 4, 7, 2, 0, 0, 0, 6, 5, 1, 4, 3, 9, 5, 6, 8, 6, 5, 0, 7, 7, 7, 6, 0, 6, 1, 0, 7, 6, 1, 4, 1, 2, 7, 8, 3, 6, 5, 0, 7, 3, 3, 0, 5, 4, 3, 0, 1, 8, 3, 6, 1, 8, 8, 1, 8, 6, 8, 3, 8, 3, 7, 1, 8, 9, 9, 3, 8, 5, 8, 0, 3, 7, 7, 6, 9, 5, 3, 1, 3, 0, 8, 5, 0, 9, 3, 3, 7, 9, 7, 0, 7, 6, 0, 4, 9, 2, 9, 2, 1, 2, 0, 0, 1, 5, 3 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS li(x) is the logarithmic integral function, extended to the whole complex plane. The corresponding imaginary part is in A257818. LINKS Stanislav Sykora, Table of n, a(n) for n = 0..2000 Eric Weisstein's World of Mathematics, Logarithmic Integral Wikipedia, Logarithmic integral function FORMULA Equals gamma + log(Pi/2) + Sum_{k>=1}((-1)^k*(Pi/2)^(2*k)/(2*k)!/(2*k)). Equals Ci(Pi/2), the maximum value of the cosine integral along the real axis. - Stanislav Sykora, Nov 12 2016 EXAMPLE 0.47200065143956865077760610761412783650733054301836188186838371... MAPLE evalf(Re(Li(I)), 120); # Vaclav Kotesovec, May 10 2015 MATHEMATICA RealDigits[Re[LogIntegral[I]], 10, 120][[1]] (* Vaclav Kotesovec, May 10 2015 *) PROG (PARI) li(z) = {my(c=z+0.0*I); \\ If z is real, convert it to complex   if(imag(c)<0, return(-Pi*I-eint1(-log(c))),   return(+Pi*I-eint1(-log(c)))); }   a=real(li(I)) CROSSREFS Cf. A001620, A019669, A094642, A257818. Sequence in context: A289523 A078220 A256040 * A246710 A139346 A133390 Adjacent sequences:  A257814 A257815 A257816 * A257818 A257819 A257820 KEYWORD nonn,cons AUTHOR Stanislav Sykora, May 10 2015 STATUS approved

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Last modified January 24 01:05 EST 2020. Contains 331178 sequences. (Running on oeis4.)