Best way to use/implement Debye function in Julia?

[stevengj]

@trg818

for l in 0:k
    ll=l
    is=is+(-1)^l *(big(ll)^n)*binomial(k,l)
end

This is a slow way to implement a power series. You always want to compute each term as a recurrence from the next. See also And Julia keeps amazing me: high precision computation - #6 by stevengj