If you ask Python to generate the 1000th term using a recursive
algorithm, it can't handle it, complaining that you've exceeded the
allowed depth of recursion (you can "call yourself" at most 999 deep).
The function x(n) invokes itself (like factorial or fibonacci).

def x(n):
    if n==1 : return 0
    return 3*(x(n-1)+2*n-3)

# x.py - lrb - 3/5/2012

if __name__ == "__main__":
    import sys
    print "Enter an integer:"
    number = sys.stdin.readline()
    print "" + str(x(int(number)))

Here's what x.py tells you when you ask it what the 999th term is.

lee@lee-Inspiron-530:/media/HP USB FD$ python x.py

Enter an integer: 999

440690273160268878963485086584048121988474010917382722554973456075609
532448901633180259437950202687321303259232290860785316984860700206303
955114241752651224675873408399440267959338258076321613758130133372529
539347042982605207698146020522057684695558163502059375160114801849018
132346298605821789418305378740276756187926194096742805466102629298972
852134694966312536457747390615453312898505588339646862703020142029890
479621367604783461882915721944003538122044057700922967618403670

C++ and Python output differ at n=34 

1: 0
2: 3
3: 18
4: 69
5: 228
6: 711
7: 2166
8: 6537
9: 19656
10: 59019
11: 177114
12: 531405
13: 1594284
14: 4782927
15: 14348862
16: 43046673
17: 129140112
18: 387420435
19: 1162261410
20: 3486784341
21: 10460353140
22: 31381059543
23: 94143178758
24: 282429536409
25: 847288609368
26: 2541865828251
27: 7625597484906
28: 22876792454877
29: 68630377364796
30: 205891132094559
31: 617673396283854
32: 1853020188851745
33: 5559060566555424
34: 16677181699666466

>>> print 3**30-3*30
205891132094559
>>> print 3**31-3*31
617673396283854
>>> print 3**32-3*32
1853020188851745
>>> print 3**33-3*33
5559060566555424
>>> print 3**34-3*34
16677181699666467
>>>

Here's a tiny-c program that uses int arrays to do multi-precision arithmetic.

multseq.tc