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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 7 |
| 4 | 57 |
| 5 | 483 |
| 6 | 4257 |
| 7 | 38675 |
| 8 | 359969 |
| 9 | 3416329 |
| 10 | 32943289 |
| 11 | 321888455 |
| 12 | 3180249409 |
| 13 | 31718822793 |
| 14 | 318934721393 |
| 15 | 3229639622847 |
| 16 | 32907617157641 |
| 17 | 337144842511850 |
| 18 | 3470986886039193 |
| 19 | 35890957497118363 |
| 20 | 372584381500477185 |
| 21 | 3881595191885835547 |
[1,0,1,7,57,483,4257,38675,359969,3416329, 32943289,321888455,3180249409,31718822793, 318934721393,3229639622847,32907617157641, 337144842511850,3470986886039193, 35890957497118363,372584381500477185, 3881595191885835547] |