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 A227574 #12 Dec 08 2023 23:36:47 %S A227574 1,5,9,1,60,1,105,1,90,1,231,1,10920,1,27,1,2550,1,4389,1,1980,1,897, %T A227574 1,19110,1,45,1,6960,1,121737,1,4590,1,57,1,19191900,1,63,1,148830,1, %U A227574 20769,1,8280,1,3525,1,603330,1,891,1,22260,1,11571,1,13050,1 %N A227574 Denominators of rationals with e.g.f. D(4,x), a Debye function. %C A227574 See the comments and the Abramowitz-Stegun link under A227573. %F A227574 a(n) = denominator(4*B(n)/(n+4)), n >= 0, with the Bernoulli numbers B(n) = A027641(n)/A027642(n). %F A227574 The e.g.f. of the rationals r(4,n) := 4*B(n)/(n+4) is D(4,x) = (4/x^4)*int(t^4/(exp(t) - 1), t=0..x). %e A227574 The rationals r(4,n), n=0..15 are: 1, -2/5, 1/9, 0, -1/60, 0, 1/105, 0, -1/90, 0, 5/231, 0, -691/10920, 0, 7/27, 0. %t A227574 A227574[n_]:=Denominator[4BernoulliB[n]/(n+4)]; %t A227574 Array[A227574,100,0] (* _Paolo Xausa_, Dec 08 2023 *) %Y A227574 Cf. A227573, A027641/A027642, A120086/A120087 (D(4,x) as o.g.f.). %K A227574 nonn,easy,frac %O A227574 0,2 %A A227574 _Wolfdieter Lang_, Jul 17 2013