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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 17 |
| 5 | 65 |
| 6 | 922 |
| 7 | 7074 |
| 8 | 106183 |
| 9 | 1248479 |
| 10 | 21144289 |
| 11 | 331763177 |
| 12 | 6441011484 |
| 13 | 124904347404 |
| 14 | 2773880604749 |
| 15 | 63538143151589 |
| 16 | 1600211849569585 |
| 17 | 42076439530000297 |
| 18 | 1189408501356380558 |
| 19 | 35214128238218917974 |
| 20 | 1106088535644470694779 |
[1,0,1,1,17,65,922,7074,106183,1248479,21144289, 331763177,6441011484,124904347404,2773880604749, 63538143151589,1600211849569585,42076439530000297, 1189408501356380558,35214128238218917974, 1106088535644470694779] |