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A269768 Decimal expansion of Sum_{n>=2} (-1)^n * zeta(n)/n!. 2

%I #13 Mar 03 2023 09:38:29

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

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

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

%N Decimal expansion of Sum_{n>=2} (-1)^n * zeta(n)/n!.

%H J. Sondow and E. W. Weisstein, <a href="http://mathworld.wolfram.com/RiemannZetaFunction.html">MathWorld: Riemann Zeta Function</a>

%F Equals Sum_{k>=1} (exp(-1/k) - 1 + 1/k).

%F Comment from _Velin Yanev_, Mar 03 2023 (Start)

%F Apparently equals 1/2 - Integral_{x=0..oo} (coth(Pi/x)*(sin(x)/x^2 - 1/x) + 1/Pi) dx.

%F The proposed expression is difficult to evaluate to arbitrary precision.

%F Maple code: evalf[50](1/2 - Int(coth(Pi/x)*(sin(x)/x^2 - 1/x) + 1/Pi, x = 0 .. infinity));

%F Mathematica code: 1/2-NIntegrate[Coth[Pi/t] (Sin[t]/t^2-1/t)+1/Pi,{t,0,Infinity},WorkingPrecision->50,MinRecursion->7]

%F (End)

%e 0.659815254349999514863844174352958996077770074088808541384121349320633989...

%p evalf(Sum(exp(-1/n)-1+1/n, n=1..infinity), 120);

%t RealDigits[NSum[Exp[-1/n] - 1 + 1/n, {n, 1, Infinity}, WorkingPrecision -> 200, NSumTerms -> 10000, PrecisionGoal -> 120, Method -> {"NIntegrate", "MaxRecursion" -> 100}]][[1]]

%Y Cf. A093720.

%K nonn,cons

%O 0,1

%A _Vaclav Kotesovec_, Mar 04 2016

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Last modified March 19 04:26 EDT 2024. Contains 370952 sequences. (Running on oeis4.)