Expansion of sin(tan(x))/cos(x).A009509Expansion of sin(tan(x))/cos(x).Terms a(0) =1a(1) =4a(2) =32a(3) =264a(4) =-9216a(5) =-1548032a(6) =-190744448a(7) =-25395878400External referencesoeis: A009509