Expansion of sin(tan(x)/cosh(x)).A009517Expansion of sin(tan(x)/cosh(x)).Terms a(0) =1a(1) =-2a(2) =32a(3) =-688a(4) =29952a(5) =-1922560a(6) =160364544a(7) =-19815696384External referencesoeis: A009517