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 A133005 #15 Jan 24 2024 12:18:43
%S A133005 1,1,3,6,45,54,63,540,405,810,13365,20412,331695,306180,65610,29160,
%T A133005 6506325,2296350,4363065,757795500,22733865,90935460,203719050,
%U A133005 9672226200,403009425,4836113100,22320522,2232052200,267009244425,6313519080,3425084100900,112696315578000,3018651310125
%N A133005 Denominators of Blandin-Diaz compositional Bernoulli numbers C_2,n.
%H A133005 Hector Blandin and Rafael Diaz, <a href="https://arxiv.org/abs/0708.0809">Compositional Bernoulli numbers</a>, arXiv:0708.0809 [math.CO], 2007-2008, p. 14, first table.
%e A133005 0, 1, -23, 56, -68/45, 193/54, -655/63, 19349/540, -57736/405, 520343/810.
%o A133005 (PARI) my(x='x+O('x^40)); apply(denominator, concat(0, Vec(serlaplace(serreverse(2*(exp(x)-1-x)/x))))) \\ _Michel Marcus_, Jan 24 2024
%Y A133005 Numerators are A133004.
%Y A133005 Cf. A132092-A132099.
%K A133005 frac,nonn
%O A133005 0,3
%A A133005 _Jonathan Vos Post_, Aug 09 2007
%E A133005 a(6) corrected and more terms from _Michel Marcus_, Jan 24 2024