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%I #6 May 18 2024 15:10:22
%S 1,5,3,2,3,5,7,6,3,0,1,4,5,9,1,4,6,1,8,6,7,9,2,2,1,7,8,6,1,6,6,9,3,6,
%T 8,0,1,2,9,9,9,9,9,8,0,1,5,0,6,5,1,7,7,1,2,3,4,4,1,7,6,1,9,2,6,7,8,4,
%U 1,5,8,0,3,9,7,4,0,9,5,3,8,5,6,8,1,9
%N Decimal expansion of Sum_{k>=0} (-1)^k*(k+2) / (2k+1)!.
%F Equals (cos(1) + 3*sin(1))/2.
%e 1.532357630145914618679221786166936801299999801506...
%t s = Sum[(-1)^k (k + 2)/(2 k + 1)!, {k, 0, Infinity}]
%t d = N[s, 100]
%t First[RealDigits[d]]
%Y Cf. A372388.
%K nonn,cons
%O 1,2
%A _Clark Kimberling_, May 12 2024
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