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 A334380 Decimal expansion of Sum_{k>=0} (-1)^k/((2*k)!!)^2. 1

%I

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

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

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

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

%C This constant is transcendental.

%H <a href="/index/Be#Bessel">Index entries for sequences related to Bessel functions or polynomials</a>

%H <a href="/index/Tra#transcendental">Index entries for transcendental numbers</a>

%F Equals BesselJ(0,1).

%e 1/(4^0*0!^2) - 1/(4^1*1!^2) + 1/(4^2*2!^2) - 1/(4^3*3!^2) + ... = 0.765197686557966551449717526...

%t RealDigits[BesselJ[0, 1], 10, 110] [[1]]

%o (PARI) besselj(0, 1) \\ _Michel Marcus_, Apr 26 2020

%Y Cf. A000165, A002454, A070910, A091681, A197036.

%K nonn,cons

%O 0,1

%A _Ilya Gutkovskiy_, Apr 25 2020

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Last modified May 14 19:25 EDT 2021. Contains 343901 sequences. (Running on oeis4.)