On platforms without seq (MacOSX, Solaris), you can emulate it using dc as follows (note the upper bound and the lower bound):

echo '[1+pdUPPER_BOUND>aq]saLOWER_BOUND 1-lax' | dc

For example:

alia:~ andrea$ echo '[1+pd5>aq]sa0 1-lax' | dc  
0  
1  
2  
3  
4  
5  
alia:~ andrea$