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Decimal expansion of Sum_{k>=0} (-1)^k / (2*(k+1)*(2*k+1)!).
1

%I #12 Apr 27 2024 08:38:57

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

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

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

%N Decimal expansion of Sum_{k>=0} (-1)^k / (2*(k+1)*(2*k+1)!).

%F Equals 1 - cos(1) = A371935/2 = 1 - A049470.

%F Equals 1/A206533. - _Hugo Pfoertner_, Apr 26 2024

%e 0.459697694131860282599063392557023396267689579382077772...

%t s = N[Sum[(-1)^k/(2(k + 1) (2 k + 1)!), {k, 0, Infinity}], 120]

%t First[RealDigits[s]]

%Y Cf. A049470, A206533, A371935.

%K nonn,cons

%O 0,1

%A _Clark Kimberling_, Apr 24 2024