OFFSET
1,1
COMMENTS
Denominators of nonzero coefficients in the series expansion around zero of cot(x/2)/2, disregarding the first term. - Fredrik Johansson, Aug 20 2006
REFERENCES
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, Tenth Printing, 1972, p. 16 (3.6.28), p. 806 (23.1.30), p. 886 (25.4.7).
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..200
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, Tenth Printing, 1972, p. 16 (3.6.28), p. 806 (23.1.30), p. 886 (25.4.7).
Zhanna Kuznetsova, and Francesco Toppan, Classification of minimal Z_2 X Z_2-graded Lie (super)algebras and some applications, arXiv:2103.04385 [math-ph], 2021.
MATHEMATICA
Join[{2}, f[n_]:=Denominator[-(-1)^n BernoulliB[2 n]/(2 n)!]; Table[f[n], {n, 30}]] (* Robert G. Wilson v, Sep 02 2004 *) (* adapted by Vincenzo Librandi, May 04 2017 *)
Join[{2}, Denominator[Table[SeriesCoefficient[x^2/(1 - E^x), {x, 0, n}], {n, 3, 25, 2}]]] (* Terry D. Grant, Jun 01 2017 *)
PROG
(Magma) [2] cat [Denominator(-(-1)^n*Bernoulli(2*n)/Factorial(2*n)): n in [1..15]]; // Vincenzo Librandi, Jun 04 2017
CROSSREFS
KEYWORD
nonn,frac,easy
AUTHOR
Wolfdieter Lang, Feb 16 2001
STATUS
approved