With 18 numbers the odds would be 1/9,075,135,300.
1 1 in 36
2 1 in 630
3 1 in 7,140
4 1 in 58,905
5 1 in 376,992
6 1 in 1,947,792
7 1 in 8,347,680
8 1 in 30,260,340
9 1 in 94,143,280
10 1 in 254,186,856
11 1 in 600,805,296
12 1 in 1,251,677,700
13 1 in 2,310,789,600
14 1 in 3,796,297,200
15 1 in 5,567,902,560
16 1 in 7,307,872,110
17 1 in 8,597,496,600
18 1 in 9,075,135,300
19 1 in 8,597,496,600
20 1 in 7,307,872,110
21 1 in 5,567,902,560
22 1 in 3,796,297,200
23 1 in 2,310,789,600
24 1 in 1,251,677,700
25 1 in 600,805,296
26 1 in 254,186,856
27 1 in 94,143,280
28 1 in 30,260,340
29 1 in 8,347,680
30 1 in 1,947,792
31 1 in 376,992
32 1 in 58,905
33 1 in 7,140
34 1 in 630
35 1 in 36
36 1 in 1