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$