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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 13 |
| 6 | 171 |
| 7 | 931 |
| 8 | 45935 |
| 9 | 1084413 |
| 10 | 155862511 |
| 11 | 10382960971 |
| 12 | 6939278572095 |
| 13 | 2203360500122299 |
| 14 | 4186526756621772343 |
| 15 | 3747344008241368443819 |
| 16 | 35041787059691023579970847 |
| 17 | 156277111373303386104606663421 |
| 18 | 4142122641757598618318165240180095 |
[1,0,1,1,7,13,171,931,45935,1084413,155862511, 10382960971,6939278572095,2203360500122299, 4186526756621772343,3747344008241368443819, 35041787059691023579970847, 156277111373303386104606663421, 4142122641757598618318165240180095] |