f(x)=e^(x)的幂级数展开式是;
e^x=1+1/1!x+x^2/2!+...+x^n/n!+.
令x=-x^3
则
f(x)=e^(-x^3)的幂级数展开式是
e^(-x^3)
=1-x^3/1!+x^6/2!+..+(-1)^n*x^(3n)/n!+...