Python: maximum recursion depth exceeded while calling a Python object

I've built a crawler that had to run on about 5M pages (by increasing the url ID) and then parses the pages which contain the info' I need.

after using an algorithm which run on the urls (200K) and saved the good and bad results I found that the I'm wasting a lot of time. I could see that there are a a few returning subtrahends which I can use to check the next valid url.

you can see the subtrahends quite fast (a little ex' of the few first "good IDs") -

510000011 # +8
510000029 # +18
510000037 # +8
510000045 # +8
510000052 # +7
510000060 # +8
510000078 # +18
510000086 # +8
510000094 # +8
510000102 # +8
510000110 # etc'
510000128
510000136
510000144
510000151
510000169
510000177
510000185
510000193
510000201

after crawling about 200K urls which gave me only 14K good results I knew I was wasting my time and need to optimize it, so I run some statistics and built a function that will check the urls while increasing the id with 8\18\17\8 (top returning subtrahends ) etc'.

this is the function -

def checkNextID(ID):
    global numOfRuns, curRes, lastResult
    while ID < lastResult:
        try:
            numOfRuns += 1
            if numOfRuns % 10 == 0:
                time.sleep(3) # sleep every 10 iterations
            if isValid(ID + 8):
                parseHTML(curRes)
                checkNextID(ID + 8)
                return 0
            if isValid(ID + 18):
                parseHTML(curRes)
                checkNextID(ID + 18)
                return 0
            if isValid(ID + 7):
                parseHTML(curRes)
                checkNextID(ID + 7)
                return 0
            if isValid(ID + 17):
                parseHTML(curRes)
                checkNextID(ID + 17)
                return 0
            if isValid(ID+6):
                parseHTML(curRes)
                checkNextID(ID + 6)
                return 0
            if isValid(ID + 16):
                par