which leads to the recurrence relation as
Some numerical values of are given as under:
m
0
1
2
3
4
5
6
-4
Formula (7.48) is explicit. It is not recommended for For there results the simple and relatively accurate formula
Since , the same formula results also from picking the value
Another set of formulas is derived by choosing in (7.37).
are given as under: 
For 
there results the simple and relatively accurate formula 
, the same formula results also from picking the value 
in (7.37).
