Question

Book: A Course in Enumeration. Author: Martin Aigner

Chapter 1 Page:60

If A(z) = $\sum \:$n≥0 $a^{n}z^{n}$, then an is the n-th coefficient of A(z), for
which we also write $a^{n}$ = [$z^{n}$]A(z). Sometimes it is useful to consider
coefficients with negative index, with the understanding that
ak = 0 for k < 0. The coefficient a0 is called the constant coefficient,
and we also write a0 = A(0). The set of all formal series over
C shall be denoted by C[[z]].

2.8 Determine 7 n Hint: Use Ση20 (n)z" (1-42)-1 /2.

Answer 1

Σ(wi21)2n 2.8 Determine ln/2] n20 Hint: Use Σ'120 ('n) zn _ (1-42)-1 /2 2. ว่า ељ