Sequence module from awesome cgkit library http://cgkit.sourceforge.net/doc2/sequence.html
Quick example
import sequence
sequences = sequence.glob('pattern or path to directory or partial name')
for seq in sequences:
ff = str(seq[0]) #Firts frame
lf = str(seq[-1]) #Last frame
name, range = seq.sequenceName() #Sequence name and Range object
path, filename = os.path.split(name)
root, ext = os.path.splitext(filename) #get extension and name
count = len(range) # Frame count - sequence length
frames = list(range)
fframe = str(frames[0]) #Firts frame digit, 1
lframe = str(frames[-1]) #Last frame digit, 89
And better examples is here http://cgkit.sourceforge.net/doc2/filesequencetools.html