Expansion of tanh(tan(x)*x)/2.

A024257

Expansion of tanh(tan(x)*x)/2.

Terms

    a(0) =0a(1) =1a(2) =4a(3) =-72a(4) =-5632a(5) =-161920a(6) =18173952a(7) =4194147328a(8) =310213328896

External references