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 A006685 M5173 #20 Jun 17 2017 09:47:40 %S A006685 24,1920,193536,66355200,13624934400,243465191424000,4944216195072000, %T A006685 9990141980442624000,39391717484295880704000, %U A006685 465236915972420822630400000 %N A006685 Coefficients for numerical integration. %D A006685 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006685 H. E. Salzer, <a href="http://dx.doi.org/10.1080/14786444508521494">Coefficients for mid-interval numerical integration with central differences</a>, Phil. Mag., 36 (1945), 216-218. %H A006685 T. R. Van Oppolzer, <a href="http://www.archive.org/stream/lehrbuchzurbahnb02oppo#page/545/mode/1up">Lehrbuch zur Bahnbestimmung der Kometen und Planeten</a>, Vol. 2, Engelmann, Leipzig, 1880, p. 545 (see denominators of numbers named P(2,2k)). %F A006685 a(n) = A002198(n) / (2*n+1). - _Sean A. Irvine_, Jun 17 2017 %Y A006685 Cf. A002197, A002198. %K A006685 nonn %O A006685 0,1 %A A006685 _N. J. A. Sloane_