login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Numerators of expansion of original Debye function D(3,x).
9

%I #24 May 01 2023 10:03:31

%S 1,-3,1,0,-1,0,1,0,-1,0,1,0,-691,0,1,0,-3617,0,43867,0,-174611,0,

%T 77683,0,-236364091,0,657931,0,-3392780147,0,1723168255201,0,

%U -7709321041217,0,151628697551,0,-26315271553053477373

%N Numerators of expansion of original Debye function D(3,x).

%C Denominators are given in A120081.

%C See the W. Lang link below for more details on the general case D(n,x), n= 1, 2, ... D(3,x) is the e.g.f. of the rational sequence {3*B(n)/(n+3)}, n >= 0. See A227570/A227571.

%D L. D. Landau, E. M. Lifschitz: Lehrbuch der Theoretischen Physik, Band V: Statistische Physik, Akademie Verlag, Leipzig, p. 195, equ. (63.5) and footnote 1 on p. 197.

%H G. C. Greubel, <a href="/A120080/b120080.txt">Table of n, a(n) for n = 0..500</a>

%H M. Abramowitz and I. A. Stegun, eds., <a href="http://www.convertit.com/Go/ConvertIt/Reference/AMS55.ASP">Handbook of Mathematical Functions</a>, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].

%H M. Abramowitz and I. A. Stegun, eds., <a href="http://www.convertit.com/Go/ConvertIt/Reference/AMS55.ASP">Handbook of Mathematical Functions</a>, National Bureau of Standards Applied Math. Series 55, Tenth Printing, 1972, pp. 998, equ. 27.1.1 for n=3, with a factor (x^3)/3 extracted.

%H Wolfdieter Lang, <a href="/A120080/a120080.pdf"> Rationals r(n), and general remarks on the e.g.f. D(n,x)</a>.

%F D(x) = D(3,x) := (3/x^3)*Integral_{0..x} (t^3/(exp(t)-1) dt.

%F a(n) = numerator(r(n)), with r(n) = [x^n]( 1 - 3*x/8 + Sum_{k >= 0} ((B(2*k)/((2*k+3)*(2*k)!))*x^(2*k) ) (in lowest terms), |x| < 2*pi. B(2*k) = A000367(k)/A002445(k) (Bernoulli numbers).

%F a(n) = numerator(3*B(n)/((n+3)*n!)), n >= 0, with the Bernoulli numbers B(n) = A027641(n)/A027642(n). See the comment on the e.g.f. D(3,x) above. - _Wolfdieter Lang_, Jul 16 2013

%e Rationals r(n): [1, -3/8, 1/20, 0, 1/1680, 0, 1/90720, 0, ...].

%t max = 39; Numerator[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 Table[Numerator[3*BernoulliB[n]/((n+3)*n!)], {n,0,50}] (* _G. C. Greubel_, May 01 2023 *)

%o (Magma) [Numerator(3*Bernoulli(n)/((n+3)*Factorial(n))): n in [0..50]]; // _G. C. Greubel_, May 01 2023

%o (SageMath)

%o def A120080(n): return numerator(3*bernoulli(n)/((n+3)*factorial(n)))

%o [A120080(n) for n in range(51)] # _G. C. Greubel_, May 01 2023

%Y Cf. A000367, A002445, A027641, A027642, A120081, A227570, A227571.

%K sign,frac

%O 0,2

%A _Wolfdieter Lang_, Jul 20 2006