OFFSET
0,4
REFERENCES
V. Mangulis, Handbook of Series, Academic Press, 1965, p. 76.
FORMULA
log(z^2/(cosh(z)-cos(z))) = Sum_{ n >= 1 } (-1)^n*B_{2n}*(2z^2)^(2n)/((4n)!2n).
a(n)=Numerator((-1)^n * Zeta(4n)/(Zeta(2n)*Pi^(2n)). - Enrique Pérez Herrero, Jun 20 2012
EXAMPLE
log(z^2/(cosh(z)-cos(z))) = -(1/360)*z^4+(1/302400)*z^8-(691/122594472000)*z^12+(3617/333456963840000)*z^16+...
CROSSREFS
KEYWORD
sign,frac
AUTHOR
N. J. A. Sloane, Oct 31 2009
STATUS
approved