This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A120081 #18 Jan 25 2025 08:26:42
%S A120081 1,8,20,1,1680,1,90720,1,4435200,1,207567360,1,6538371840000,1,
%T A120081 423437414400,1,67580611338240000,1,35763659520196608000,1,
%U A120081 6155242080686899200000,1,117509166994931712000000,1,15244417230585693025075200000,1,1799300365026394374144000000
%N A120081 Denominators of expansion for original Debye function (n=3).
%C A120081 Numerators are given in A120080.
%C A120081 See A120070 for the definition of the Debye function D(x)=D(3,x) and references and links.
%H A120081 G. C. Greubel, <a href="/A120081/b120081.txt">Table of n, a(n) for n = 0..500</a>
%F A120081 a(n) = denominator(r(n)), with r(n) = [x^n]( 1 - 3*x/8 + Sum_{k >= 1} (3*B(2*k)/((2*k+3)*(2*k)!))*x^(2*k) ), where B(2*k) = A000367(k)/A002445(k) (Bernoulli numbers).
%F A120081 a(n) = denominator( 3*Bernoulli(n)/((n+3)*n!) ), n >= 0. - _G. C. Greubel_, May 01 2023
%t A120081 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 *)
%t A120081 Table[Denominator[3*BernoulliB[n]/((n+3)*n!)], {n,0,50}] (* _G. C. Greubel_, May 01 2023 *)
%o A120081 (Magma) [Denominator(3*Bernoulli(n)/((n+3)*Factorial(n))): n in [0..50]]; // _G. C. Greubel_, May 01 2023
%o A120081 (SageMath)
%o A120081 def A120081(n): return denominator(3*bernoulli(n)/((n+3)*factorial(n)))
%o A120081 [A120081(n) for n in range(51)] # _G. C. Greubel_, May 01 2023
%Y A120081 Cf. A000367, A002445, A120080.
%K A120081 nonn,easy,frac
%O A120081 0,2
%A A120081 _Wolfdieter Lang_, Jul 20 2006