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A120081 Denominators of expansion for original Debye function (n=3). 3


%S 1,8,20,1,1680,1,90720,1,4435200,1,207567360,1,6538371840000,1,

%T 423437414400,1,67580611338240000,1,35763659520196608000,1,

%U 6155242080686899200000,1,117509166994931712000000,1

%N Denominators of expansion for original Debye function (n=3).

%C Numerators are given in A120080.

%C See A120070 for the definition of the Debye function D(x)=D(3,x) and references and links.

%F a(n)=denominator(r(n)), with r(n):=[x^n](1-3*x/8+sum((B(2*k)/((2*k+3)*(2*k)!))*x^(2*k),0,..infinity)). B(2*k):=A000367(k)/A002445(k) (Bernoulli numbers).

%t max = 26; Denominator[ CoefficientList[ Integrate[ Normal[ Series[ (3*(t^3/(Exp[t] - 1)))/x^3, {t, 0, max}]], {t, 0, x}], x]](* _Jean-François Alcover_, Oct 04 2011 *)

%K nonn,easy,frac

%O 0,2

%A _Wolfdieter Lang_, Jul 20 2006

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Last modified December 2 07:16 EST 2021. Contains 349437 sequences. (Running on oeis4.)