ADS_power_series.sagews

R = PowerSeriesRing(QQ, 'x'); R

Power Series Ring in x over Rational Field

g=R.random_element(6);g

-1/2 - 7/3*x^2 + 9*x^4 - 5*x^5 + O(x^6)

g^(-1)

f*f

x^2 + 4*x^3 + 10*x^4 + 20*x^5 + 35*x^6 + 56*x^7 + 70*x^8 + 76*x^9 + 73*x^10 + 60*x^11 + 36*x^12

def (i)
=0
 forjn(1+1):
s+=j*2^(-j)
rturn
d(20)

rn(1,21)