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A120081 Denominators of expansion for original Debye function (n=3). 3
1, 8, 20, 1, 1680, 1, 90720, 1, 4435200, 1, 207567360, 1, 6538371840000, 1, 423437414400, 1, 67580611338240000, 1, 35763659520196608000, 1, 6155242080686899200000, 1, 117509166994931712000000, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Numerators are given in A120080.

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

LINKS

Table of n, a(n) for n=0..23.

FORMULA

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).

MATHEMATICA

max = 26; Denominator[ CoefficientList[ Integrate[ Normal[ Series[ (3*(t^3/(Exp[t] - 1)))/x^3, {t, 0, max}]], {t, 0, x}], x]](* Jean-Fran├žois Alcover, Oct 04 2011 *)

CROSSREFS

Sequence in context: A034433 A282942 A225912 * A173206 A288423 A081963

Adjacent sequences:  A120078 A120079 A120080 * A120082 A120083 A120084

KEYWORD

nonn,easy,frac

AUTHOR

Wolfdieter Lang, Jul 20 2006

STATUS

approved

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Last modified October 16 00:29 EDT 2021. Contains 348034 sequences. (Running on oeis4.)