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A036243 Denominator of fraction equal to the continued fraction [ 0, 2, 4, ...2n ]. 5

%I

%S 2,9,56,457,4626,55969,788192,12667041,228794930,4588565641,

%T 101177239032,2432842302409,63355077101666,1776375001149057,

%U 53354605111573376,1709123738571497089,58163561716542474402,2095597345534100575561

%N Denominator of fraction equal to the continued fraction [ 0, 2, 4, ...2n ].

%F a(n) = b(n+1) where b(n) = K(n,1)*I(0,1) - (-1)^n*I(n,1)*K(0,1), K(n,x) and I(n,x) Bessel functions. # _Peter Luschny_, Sep 14 2014

%p b := n -> BesselK(n,1)*BesselI(0,1)-(-1)^n*BesselI(n,1)* BesselK(0,1); A036243 := n -> b(n+1):

%p seq(round(evalf(A036243(n),99)),n=1..18); # _Peter Luschny_, Sep 14 2014

%t Table[Denominator[FromContinuedFraction[Range[0,2n,2]]],{n,20}] (* _Harvey P. Dale_, Feb 18 2016 *)

%o (PARI) a(n)=contfracpnqn(vector(n+1,i,2*i-2))[2,1] \\ _M. F. Hasler_, Feb 08 2011

%Y Cf. A036242.

%K frac,nonn

%O 1,1

%A _Jeff Burch_

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Last modified July 12 21:31 EDT 2020. Contains 335669 sequences. (Running on oeis4.)