series(sin(sinh(x))-sinh(sin(x)),x=0,7)
1/-45*x^7+x^8*order_size(x)
series(ln(cos(x))/exp(x+x^2),x=0,4)
1/-2*x^2+1/2*x^3+1/6*x^4+x^5*order_size(x)