# Fungrim entry: 6202cb

${c}_{n} = \frac{1}{n {a}_{0}} \sum_{k=1}^{n} \left(\frac{3 k}{2} - n\right) {a}_{k} {c}_{n - k}\; \text{ where } {c}_{n} = [{x}^{n}] \sqrt{A},\;{a}_{n} = [{x}^{n}] A$
Assumptions:$A \in \mathbb{C}[[x]] \;\mathbin{\operatorname{and}}\; [{x}^{0}] A \ne 0 \;\mathbin{\operatorname{and}}\; n \in \mathbb{Z}_{\ge 1}$
TeX:
{c}_{n} = \frac{1}{n {a}_{0}} \sum_{k=1}^{n} \left(\frac{3 k}{2} - n\right) {a}_{k} {c}_{n - k}\; \text{ where } {c}_{n} = [{x}^{n}] \sqrt{A},\;{a}_{n} = [{x}^{n}] A

A \in \mathbb{C}[[x]] \;\mathbin{\operatorname{and}}\; [{x}^{0}] A \ne 0 \;\mathbin{\operatorname{and}}\; n \in \mathbb{Z}_{\ge 1}
Definitions:
Fungrim symbol Notation Short description
Sum$\sum_{n} f(n)$ Sum
Sqrt$\sqrt{z}$ Principal square root
PowerSeries$K[[x]]$ Formal power series
CC$\mathbb{C}$ Complex numbers
ZZGreaterEqual$\mathbb{Z}_{\ge n}$ Integers greater than or equal to n
Source code for this entry:
Entry(ID("6202cb"),
Formula(Where(Equal(Subscript(c, n), Mul(Div(1, Mul(n, Subscript(a, 0))), Sum(Mul(Mul(Sub(Div(Mul(3, k), 2), n), Subscript(a, k)), Subscript(c, Sub(n, k))), For(k, 1, n)))), Equal(Subscript(c, n), SeriesCoefficient(Sqrt(A), x, n)), Equal(Subscript(a, n), SeriesCoefficient(A, x, n)))),
Variables(A, n),
Assumptions(And(Element(A, PowerSeries(CC, x)), NotEqual(SeriesCoefficient(A, x, 0), 0), Element(n, ZZGreaterEqual(1)))))

## Topics using this entry

Copyright (C) Fredrik Johansson and contributors. Fungrim is provided under the MIT license. The source code is on GitHub.

2020-04-08 16:14:44.404316 UTC