A.2 Permutations 307
Sij
j
i 12345
1 1
2 11
3 131
4 1761
5 11525101
Further values are given by Abramowitz and Stegun. Stirling numbers ap-
pear in Section 5.6.3 on distinct matrices with nondistinct determinants
and in Appendix A.6.
The matricessn(x) andSn(x) are defined as follows:
sn(x)=
[
sijx
i−j
]
n
=
1
−x 1
2 x
2
− 3 x 1
− 6 x
3
11 x
2
− 6 x 1
24 x
4
− 50 x
3
35 x
2
− 10 x 1
...............................
n
,
Sn(x)=
[
Sijx
i−j
]
n
=
1
x 1
x
2
3 x 1
x
3
7 x
2
6 x 1
x
4
15 x
3
25 x
2
10 x 1
.........................
n
.
A.2 Permutations
Inversions, the Permutation Symbol
The firstnpositive integers 1, 2 , 3 ,...,n, can be arranged in a linear se-
quence inn! ways. For example, the first three integers can be arranged in
3! = 6 ways, namely
123
132
213
231
312
321
LetNndenote the set of the firstnintegers arranged in ascending order of
magnitude,
Nn=
{
123 ···n