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Decimal expansion of Sum_{n>=1} sin(sin(n)/n).
4

%I #31 Mar 22 2021 03:18:53

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

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

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

%N Decimal expansion of Sum_{n>=1} sin(sin(n)/n).

%C Abel summation shows the series is convergent.

%D Konrad Knopp, Theory and Application of Infinite Series, Blackie, 1928, p. 313.

%D Jean-Marie Monier, Analyse, Tome 3, 2ème année, MP.PSI.PC.PT, Dunod, 1997, Exercice C.3.7 2.3.b)4. p. 309.

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Summation_by_parts">Summation by parts</a>.

%e 0.96139431594573654724764595316154730686858269301058...

%o (Magma) nDgtsOutput:=110; nDgtsPrecision:=nDgtsOutput+10; SetDefaultRealField(RealField(nDgtsPrecision)); kMax:=Ceiling(1.395*nDgtsPrecision-3); mMax:=Ceiling(1.5*kMax); sum:=0.0; S1:=[0.0 : j in [1..kMax]]; n:=0; for m in [1..mMax] do S2:=S1; for k in [1..355] do n:=n+1; sum+:=Sin(Sin(n)/n); end for; S1[1]:=sum; for j in [1..kMax-1] do S1[j+1]:=(S2[j]+S1[j])/2; end for; end for; ChangePrecision(S1[#S1], nDgtsOutput); // The constants 1.395 and 1.5 were empirically derived; 355 is used because 355/Pi is very close to an odd integer. - _Jon E. Schoenfield_, Mar 21 2021

%Y Cf. A070751, A070752, A096418, A248946.

%K nonn,cons

%O 0,1

%A _Bernard Schott_, Mar 18 2021

%E a(3)-a(104) from _Jon E. Schoenfield_, Mar 20 2021