Summing polynomials [closed]
I have a ´Univariate Polynomial Ring in t over Symbolic Ring´
sage: cj_t = (-1)**(j-1)/factorial(j-1)*(-j+a)**(j-1/2)*exp(-j)*(t+j)**(-1)
How can I compute the sum over j from 1 to N?
sage: sum([cj_t for j in [1..N]])
(Python syntax) doesn't work either.