From the expansion of sin(sin(x)*x).

A009484

From the expansion of sin(sin(x)*x).

Terms

    a(0) =0a(1) =2a(2) =-4a(3) =-114a(4) =3352a(5) =-35270a(6) =-2244012a(7) =198654470a(8) =-8021832016a(9) =-150983244558

External references