OFFSET
0,2
FORMULA
a(n) = denominator [x^n] (cosh(2*sqrt(x)) - 2*cosh(sqrt(x)) + 1)/x.
EXAMPLE
r(n) = 1, 7/12, 31/360, 127/20160, 73/259200, 2047/239500800, 8191/43589145600, ...
MAPLE
gf := (4*sinh(sqrt(x)/2)^2*cosh(sqrt(x)))/x: ser := series(gf, x, 40):
seq(denom(coeff(ser, x, n)), n=0..14);
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
Peter Luschny, Oct 05 2019
STATUS
approved